Content selection method, content selection requesting station, content providing station, content switching indication apparatus, program, computer-readable recording medium on which program is recorded, and network system

ABSTRACT

When the operator pushes a switching button provided on a controller, a local communication station selects a remote communication station in accordance with a predetermined order, and in the remote communication station, a device is selected in accordance with a predetermined order. When the operator pushes the switching button provided on the controller again, a message that switching to all devices in the remote communication station has been completed is transmitted to the local communication station, and in accordance with the foregoing order, a remote communication station, which is a remote communication station to be selected next, is selected. In the remote communication station concerned, a device is selected in the same manner in accordance with a predetermined order. With this arrangement, it is possible to easily select a desired content even if contents such as devices are located at a plurality of stations in a dispersed manner.

TECHNICAL FIELD

The present invention relates to a content selection method forselecting a desired content from among contents that a plurality ofdevice providing stations have, a content selection requesting station,a content providing station, a content switching instruction device, aprogram, a computer-readable recording medium storing the program, and anetwork system.

BACKGROUND ART

A content such as a video recorder and a player, for example, isconnected to a television set for the use of the content. In this case,with one television set, reproduction of a video for viewing by usingthe television set is impossible while a television broadcast isreceived by the television set. Even with two television sets, when oneof the television sets is connected to a video player, reproduction of avideo for viewing by using the other television set which is notconnected to the video player is impossible.

On the contrary, a technique disclosed in patent document 1 given belowenables reproduction on a television receiver on hand from a videodevice at a distant location through wireless communications.

(Patent Document 1)

Japanese Laid-Open Patent Application No. 134502/2000

(Tokukai 2000-134502; published on May 12, 2000)

However, the conventional technique provides a selection of devicesbetween the two stations: the video device at a distant location and thetelevision receiver on hand. If devices targeted for remote control arelocated at a plurality of stations in a dispersed manner, an operatormust take the following steps: checking about which station has a devicethat he wants, selecting the station concerned, and selecting the devicethat he wants. This raises the problem that it is impossible to easilyselect a desired device.

DISCLOSURE OF INVENTION

In order to solve the aforementioned problems, an object of the presentinvention is to provide a content selection method, a content selectionrequesting stations a content providing station, a content switchinginstruction device, a program, a computer-readable recording mediumstoring the program, a network system, each of which allows desiredcontents to be selected easily even if contents are located at aplurality of stations in a dispersed manner.

In order to solve the aforementioned problems, a content selectionmethod, according to the present invention, in which a content selectionrequesting station selects from among a plurality of content providingstations, includes the steps of: the content selection requestingstation storing a selection rule for selecting from among the contentproviding stations; the content selection requesting station receiving acontent selection request entered by an operator; the content selectionrequesting station selecting one of the content providing stations inaccordance with the selection rule; and the content selection requestingstation transmitting the content selection request to the thus selectedone of the content providing stations.

With this arrangement, when the operator enters the content selectionrequest into the content selection requesting station, the contentselection requesting station selects a content in one of the contentproviding stations in accordance with the selection rule. Thus, theoperator is only required to know which content he wants to select, andis not required to know which station has the content he wants toselect. Thus, it is possible to select the desired content easily evenif the contents are located at a plurality of the stations in thedistributed manner.

Moreover, a content selection requesting station, according to thepresent invention, which selects a desired content from among contentsthat a plurality of content providing stations have, is so arranged thatthe content selection requesting station transmits a content selectionrequest to the content providing station according to the contentselection method.

With this arrangement, the content selection requesting stationtransmits the content selection request to the content providingstation, and receives, one by one, what are contained in the contentsthat the content providing station has. Thus, the operator is onlyrequired to know which content he wants to select, and is not requiredto know which station has the content he wants to select. Thus, it ispossible to select the desired content easily even if the contents arelocated at a plurality of the stations in the distributed manner.

A content providing station, according to the present invention, which,when selected by a content selection requesting station, transmits, tothe content selection requesting station, what is contained in a contentthat the content providing station has, is arranged such that thecontent providing station receives a content selection request from thecontent selection requesting station according to the content selectionmethod.

With this arrangement, if the content providing station is selected bythe content selection requesting station, the content providing stationselects, one by one, the contents that it has, and then the contentproviding station transmits, to the content selection requestingstation, what are contained in the contents. Thus, the operator is onlyrequired to know which content he wants to select, and is not requiredto know which station has the content he wants to select. Thus, it ispossible to select the desired content easily even if the contents arelocated at a plurality of the stations in the distributed manner.

Furthermore, a content switching instruction device, according to thepresent invention, is for use in the content selection method, andtransmits, to the content selection requesting station, a contentswitching instruction given by the operator.

With this arrangement, the operator is only required to always performthe same operation and send the same instruction to the contentselection requesting station. Each station judges whether or not thecontent providing station still has the content to select and whether ornot there still remains an unselected content providing station. If thecontent providing station has no more content providing station orcontent to select, the station or content is switched to the contentproviding station to be selected next or the content to be selectednext. Thus, the operator is only required to do the same operation suchas pushing the same button, turning the same dial in the same direction,or the like operation, and it is unnecessary to perform again thestation selection operation and go back to the content selectionoperation, every time the content providing stations are switched over.Therefore, it is possible to select the desired content more easily.

For a fuller understanding of the nature and advantages of theinvention, reference should be made to the ensuing detailed descriptiontaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating an example of a configuration ofa video receiving side.

FIG. 2 is a block diagram illustrating an example of a configuration ofa video transmitting side.

FIG. 3 is a diagram illustrating timings of respective processes.

FIG. 4 is a flowchart illustrating video reception starting process onthe video receiving side.

FIG. 5 is a flowchart illustrating video reception starting process onthe video receiving side.

FIG. 6 is a flowchart illustrating video reception starting process onthe video receiving side.

FIG. 7 is a flowchart illustrating video reception termination processon the video receiving side.

FIG. 8 is a flowchart illustrating video transmission starting processon the video transmitting side.

FIG. 9 is a flowchart illustrating video transmission starting processon the video transmitting side.

FIG. 10 is a flowchart illustrating video transmission terminationprocess on the video transmitting side.

FIG. 11 is diagram illustrating an example of a packet structure.

FIG. 12 is a block diagram illustrating an example of a systemconfiguration.

FIG. 13 is a block diagram illustrating an example of a configuration ofa communication station.

FIG. 14 is a flowchart illustrating a device switching process on thelocal communication station side.

FIG. 15 is a flowchart illustrating a device switching process on theremote communication station side.

FIG. 16 is a diagram illustrating an order in which exchanges of dataare carried out between the communication stations.

FIG. 17 is a diagram illustrating an example of a device settingmanagement table.

FIG. 18 is a diagram illustrating an example of a selection ordermanagement table.

FIG. 19 is a diagram illustrating an example of a device settingmanagement table.

FIG. 20 is a diagram illustrating an example of a selection ordermanagement table.

FIG. 21 is a diagram illustrating an example of a device settingmanagement table.

FIG. 22 is a diagram illustrating an example of a selection ordermanagement table.

FIG. 23 is a plan view illustrating an example of a general view of acontroller.

FIG. 24 is a plan view illustrating an example of a general view of acontroller.

FIG. 25 is a diagram illustrating an example of a selection ordermanagement table.

FIG. 26 is a diagram illustrating an example of a selection ordermanagement table.

FIG. 27 is a diagram illustrating an example of a selection ordermanagement table.

FIG. 28 is a diagram illustrating an example of a device settingmanagement table.

FIG. 29 is a diagram illustrating an example of a device settingmanagement table.

FIG. 30 is a diagram illustrating an example of a device settingmanagement table.

FIG. 31 is a diagram illustrating an example of a device settingmanagement table.

FIG. 32 is a diagram illustrating an example of a device settingmanagement table.

FIG. 33 is a diagram illustrating an example of a device settingmanagement table.

FIG. 34 is a diagram illustrating an example of a device settingmanagement table.

BEST MODE FOR CARRYING OUT THE INVENTION

The following will describe one embodiment of the present invention withreference to FIGS. 1 through 34.

The present embodiment is such that a content selection requestingstation (local communication station) selects a content that it wantsfrom among contents of a plurality of content providing stations (remotecommunication stations).

The connection target (content) is, for example, an apparatus (hardware)which is connected via a connection code or the like where appropriateto a communication device that is the content providing station, andexamples of the apparatus include a video recording and reproducingapparatus such as video tape deck and DVD player. For example, such ausage pattern can be taken that in a situation where an operator is in aroom where there is a television receiver, but not a DVD player, theoperator operates a DVD player placed in another room throughcommunications to view images of the DVD player on the televisionreceiver placed in the room where the operator is. In this case, thereproduction as described above can be realized by an arrangement inwhich a wireless communication device (station) as a connection targetselection requesting station is placed in the room where the operatoris, and a wireless communication device (station) as a connection targetproviding station is placed in the room where the DVD player is placed,so that both of the wireless devices communicate with each other. Notethat, communications between the wireless devices may be wiredcommunications.

The following will describe a structure of such a video reproducingapparatus, taking a configuration of a system built for the videoreproducing apparatus as an example. In this case, the connection targetselection requesting station is a communication station on a videoreceiving side, and each connection target providing station is acommunication station on a video transmitting side. Note that, forconvenience, the following descriptions assume that one particularstation is a connection target selection requesting station (localcommunication station), and the other plural stations are connectiontarget providing stations (remote communication stations). However, thepresent invention, not limited to this arrangement, may be arranged suchthat in the same configuration, any stations can be local station orremote station.

First, the following will describe an outline with reference to FIG. 16.In the present embodiment, when the operator pushes a switching buttonon a controller, a local communication station A selects a remotecommunication station C in accordance with a predetermined order, and inthe remote communication station C, a device f is selected in accordancewith a predetermined order. When the operator pushes the switchingbutton provided on the controller again, a message that switching to alldevices in the remote communication station C has been completed istransmitted to the local communication station A, and in accordance withthe foregoing order, a remote communication station B, which is a remotecommunication station to be selected next, is selected. In the remotecommunication station b, a device a is selected in the same manner inaccordance with a predetermined order. With this arrangement, it ispossible to easily select a desired content even if contents such asdevices are located at a plurality of stations in a dispersed manner.

Next, detailed descriptions will be given below.

FIG. 3 illustrates a timing diagram (a diagram illustrating a sequenceof message transmissions and contents thereof) in processes which aredescribed below. In FIG. 3, (1) Initial setting, (2) Scan, Join,Authentication, and Association process, (3) Device informationcollection process, (4) Video transmission starting process, and (5)Video transmission termination process are provided in chronologicalorder. The following description will be given according to thisclassification. Note that, the following descriptions assume that eachprocess is performed appropriately in accordance with steps illustratedin each flowchart.

(Initial Setting)

First, (1) initial setting in FIG. 3 will be described below.

The following will describe the present embodiment, assuming that powerto the communication station is turned on. The state where power to thecommunication station is turned on indicates a state where in thecommunication station, a wireless section can receive a receivedwireless signal and analyze the content of the received wireless signal,and in the communication station, a control signal input section canreceive a received control signal and analyze the content of thereceived control signal. For the purpose of reduction in powerconsumption or other purpose, blocks in part which are not necessary forthe above operation or all blocks may hold standby. In this case, theblocks are arranged so as to be activated according to the judgment of acommunication station control section 1104, when they become necessary.In any order, the communication station on the video transmitting sideand the communication station on the video receiving side can be turnedon. Further, even if there are a plurality of communication stations onthe video transmitting side and communication station on the videoreceiving side on a network, they can be turned on in any order.

FIG. 1 is a block diagram of a video receiving side in the presentembodiment, and FIG. 2 is a block diagram of a vide transmitting side inthe present embodiment. In FIG. 1, a controller A 1200 is a controllerof a communication station A 1100, and a controller a 1300 is acontroller of a device a 2300 which exists on the video transmittingside. In the present embodiment, on the video receiving side, onecommunication station is connected to one display device. However, thecommunication station may be connected to a plurality of displaydevices. On the video receiving side, there is one communication stationcontroller for one communication station. However, there may be aplurality of communication station controllers for one communicationstation. Further, the controller is generally assumed to be a remotecontroller, and may be included in the communication station. Thecommunication station may include both built-in controller and remotecontroller. On the video transmitting side, one communication station isconnected to three devices. However, any number of devices can beconnected to the communication station on the video transmitting side,and any number of devices are actually connected to the communicationstation on the video transmitting side.

As to the video receiving side, a flow of the process described belowcorresponds to a flowchart illustrated in FIG. 4, and as to the videotransmitting side, a flow of the process described below corresponds toa flowchart illustrated in FIG. 8.

(SSID Setting)

Before using the system, the user performs settings of various networkparameters for network establishment and network security. In thepresent embodiment, these processes will be described, taking IEEE802.11 as an example. In some cases, the user enters a network name todesignate a device group for identifying communication stations to beconnected to the network. For example, according to the IEEE 802.11,communication stations to be connected to one wireless network mustinclude a network name termed “SSID” set to the same value. In thepresent embodiment, the SSID is set in the following manner (S101,S151). A value of the SSID that varies depending on products is recordedin a connection information storage section 1202 of the controller A1200 at the manufacture of products or other timing. To set the SSID tothe communication station A 1100, the user performs an operation forsetting the SSID by means of a user input section 1203 of the controllerA 1200 in a location where the control signal input section 1102 of thecommunication station A 1100 and a control signal output section 1201 ofthe controller A 1200 can communicate with each other. Examples of thisoperation include a push of a “SSID Setting Button” provided on the userinput section 1203. A controller control section 1204 having detectedthe SSID setting operation performed by the user by means of the userinput section 1203 reads, from the connection information storagesection 1202, the SSID having been recorded at the manufacture, convertsthe value of the SSID into an infrared signal, and causes the controlsignal output section 1201 to output the infrared signal. This infraredsignal is received by the control signal input section 1102 of thecommunication station A 1100 and is notified to the communicationstation control section 1104. From this signal, the communicationstation control section 1104 detects the value of the SSID and stores itin a communication station A's information storage section 1101. To setthe SSID of the same value as the value set to the communication stationA 1100, as an SSID of the communication station B 2100, the userperforms an operation for setting of the SSID by means of the user inputsection 1203 of the controller A 1200 in a location where a controlsignal input section 2107 of the communication station B 2100 and thecontrol signal output section 1201 of the controller A 1200 cancommunicate with each other. In the communication station B 2100, theSSID is stored in a communication station B's information storagesection 2104 in the same manner as in the communication station A1100.Thereafter, the communication station A 1100 and the communication B2100 establish a network by a method defined by the IEEE 802.11.Detailed descriptions of network establishment process are omitted;however, communications between communication stations of mutuallydifferent SSIDs are not permitted. In the present case, thecommunication station A 1100 acquires the SSID from the communicationstation A's information storage section 1101, and the communicationstation B 2100 acquires the SSID from the communication station B'sinformation storage section 2104, so that the SSID used by thecommunication station A 1100 and the communication station B 2100 in thenetwork establishment process becomes the same SSID, allowing thecommunication station A 1100 and the communication station B 2100 to beconnected to the same network. To establish another networksimultaneously, when the user uses another controller to perform theforegoing SSID setting process, another SSID is set since an SSIDrecorded in the connection information storage section of eachcontroller varies depending upon products. This avoids closed lines inthe communications, caused by the use of one SSID on a plurality ofnetworks. The present embodiment has described the process for setting anetwork between two communication stations. However, the operation forSSID setting, by means of one controller, performed with respect to allof the communication stations which want connection to one and the samenetwork allows all of the communication stations to be connect to oneand the same network. In such a case, the SSID setting may be performedusing a controller of any communication station as long as the SSID isset using the same controller with respect to all of the communicationstations.

(WEP Key Setting)

To encrypt data for transmission to prevent tapping during datatransmission and reception on the network, a key used for the encryptionmust be common between a transmission station and a reception station.For example, according to the IEEE 802.11, WEP (Wired EquivalentPrivacy) encryption scheme is used (S102, S152). In this encryptionscheme, a transmission station encrypts data using a predetermined valueas a key so as to transmit the data. A reception station decrypts datausing a predetermined value as a key. Data encrypted using a certain keycan be restored to its original data by using the same key. However, ifthe key is different, the original data cannot be restored. Therefore,encryption using a key known only by the transmission station and thereception station eliminates tapping by a third party. In such a case,for sharing of a common key between the transmission station and thereception station, the following method will be used in the same manneras the previous SSID setting method in the present embodiment. A valueof a WEP key which varies depending on products is recorded in theconnection information storage section 1202 of the controller A 1200 atthe manufacture of products or other timing. To set the WEP key to thecommunication station A 1100, the user performs an operation for settingof the WEP key by means of the user input section 1203 of the controllerA 1200 in a location where the control signal input section 1102 of thecommunication station A 1100 and the control signal output section 1201of the controller A 1200 can communicate with each other. Examples ofthis operation include a push of a “WEP Key Setting Button” provided onthe user input section 1203. The controller control section 1204 havingdetected the WEP key setting operation performed by the user by means ofthe user input section 1203 reads, from the connection informationstorage section 1202, the WEP key having been recorded at the shipment,converts the value of the WEP key into an infrared signal, and causesthe control signal output section 1201 to output the infrared signal.This infrared signal is received by the control signal input section1102 of the communication station A 1100 and is notified to thecommunication station control section 1104. From this signal, thecommunication station control section 1104 detects the value of the WEPkey and stores it in the communication station A's information storagesection 1101. To set the WEP key of the same value as the value set tothe communication station A 1100, as a WEP key of the communicationstation B 2100, the user performs an operation for setting the SSID bymeans of the user input section 1203 of the controller A 1200 in alocation where the control signal input section 2107 of thecommunication station B 2100 and the control signal output section 1201of the controller A 1200 can communicate with each other. In thecommunication station B 2100, the WEP key is stored in the communicationstation B's information storage section 2104 in the same manner as inthe communication station A1100. Thereafter, for example, in the casewhere encryption is required in transmitting data from the communicationstation B 2100 to the communication station A 1100, the communicationstation B 2100 encrypts data using the WEP key acquired from thecommunication station B's information storage section 2104 and transmitsthe encrypted data. This allows the communication station A 1100 torestore the encrypted data to its original form by decrypting the datausing the WEP key acquired by the communication station A's informationstorage section 1101. However, other communication stations which arenot subjected to WEP key setting by means of the controller A 1200cannot restore this data, allowing for communications with securityensured between the communication station B 2100 and the communicationstation A 1100. To perform further encryption using another WEP keysimultaneously, when the user uses another controller to perform theforegoing WEP key setting process, another WEP key is set since the WEPkey recorded in the connection information storage section of eachcontroller varies depending upon products. With this arrangement, evenwhen there are plural combinations of the transmission station and thereception station on the network, they can perform transmissions withsecurity ensured. The present embodiment has described the process forsharing the WEP key between two communication stations. However, theoperation for WEP key setting, by means of one controller, performedwith respect to all of the communication stations which want to shareone WEP key allows all of the communication stations to share one WEPkey. In such a case, the SSID setting may be performed using acontroller of any communication station as long as the WEP key is setusing the same controller with respect to all of the communicationstations.

The present embodiment has described an example of independentlyperforming the SSID setting and the WEP key setting. However, if onebutton provided on the user input section 1203 of the controller A 1200triggers successively performed SSID transmission and WEP keytransmission, the SSID setting and the WEP key setting can be executedby the user at a push of the button. In a system using IEEE 802.11 as anetwork, items to be set have been shown above. In the case of the useof another network system, if network establishment and parametersetting for security are required, they are set in advance at thisstage.

(Communication Station User Name Setting)

The user enters a communication station user name at a later time fordesignation of a communication station to be connected and for easyidentification of a communication station connected to his/her ownstation (S103, S153). The communication station user name is notnumerical values or null character string, but a nickname or the likefor a communication station, which is easy for the user to understand,such as “Communication station in children's room on the second floor”.For example, to enter the communication station user name of thecommunication station A 1100, the user performs character stringentering operation using the user input section 1203 of the controller A1200. This operation is converted into a control signal by thecontroller control section 1204, and the control signal is outputtedfrom the control signal output section 1201. When the control signalinput section 1102 of the communication station A 1100 receives thissignal, the communication station control section 1104 analyzes thereceived signal, converts it into a communication station user name suchas character string, and stores the communication station user name inthe communication station A's information storage section 1101. Notethat, it is desirable that registration of the communication stationuser name is performed when a communication station is activated for thefirst time. However, the registration may be performed at the othertiming. Further, when registration of the communication station username has not been performed, it is considered to perform communicationsusing a default value having been set during manufacture of the product.

(Connection to Device)

Next, the user makes connections between the wireless station and thedisplay device and between the wireless station and the controller onthe video receiving side (S104). In the present embodiment, it isassumed that on the video receiving side, a state of readiness fortransmission of a video signal from the video signal output section 1108of the communication station A 1100 to a video signal input section 1402of the display device 1400 means completion of connections between thecommunication station A 1100 and the display device 1400. The presentembodiment assumes that this connection is wired connection. However,the connection may be wireless connection. Further, the presentembodiment assumes that the controller is a remote controller using aninfrared signal, so that it is not particularly necessary to perform aprocess for connection between the control signal output section 1201 ofthe controller A 1200 and the control signal input section 1102 of thecommunication station A 1100 and connection between the control signaloutput section 1301 of the controller a 1300 and the control signalinput section 1102. However, if there arises necessity for performingsome connection between the controller and the communication station,the connection process is performed at this stage. This connectionprocess indicates, if the controller is wire-connected to thecommunication station, for example, a process of connecting thecontroller and the communication station to each other through a cable.

Further, the user makes connections between the communication stationand devices on the video transmitting side (S154). In the presentembodiment, the user makes connections between the communication stationB 2100 and the device a 2300, between the communication station B 2100and a device b 2400, and between the communication station B 2100 and adevice a 2500. It is assumed that a state of readiness for transmissionof a video signal from a video signal output section 2301 of the devicea 2300 to a video signal input section 2100 of the communication stationB 2100 and readiness for transmission of a control signal from a controlsignal output section 2113 of the communication station B 2100 to acontrol signal input section 2304 of the device a 2300 means completionof connections between the communication station B 2100 and the device a2300. In the same manner, connections are performed between thecommunication station B 2100 and the device b 2400 and between thecommunication station B 2100 and the device c 2500. The process forconnections to the devices on the video transmitting side and theprocess for connection to the device on the video receiving side can beperformed in any order. Also, connections of the devices to thecommunication station B can be performed in any order.

(Plug)

The communication station on the video transmitting side collects andstores therein sets of information on devices connected to itself, so asto respond to an inquiry from other communication station (S155).

In the present embodiment, a connection port which connects between thecommunication station and the device is termed “plug”. A plurality ofplugs may be provided to each communication station, and thecommunication station assigns plug IDs to the respective plugs so as tomanage the plugs. The communication station manages each set ofinformation on a device by each plug and this information is termed“plug information”. In the present embodiment, plugs correspond to thevideo signal output section 1108 and the video signal input sections2110, 2112, and 2114, so that for the sets of plug information, entriesare prepared corresponding to the video signal output section and thevideo signal input section, provided to each communication station. Forexample, in the communication station 1100 on the video receiving side,an entry corresponding to the display device connected to the videosignal output section 1108 is termed “plug information 1”, and in thecommunication station 2100 on the video transmitting side, an entrycorresponding to the device a connected to the video signal inputsection 2110 is termed “plug information 1”.

The contents of the plug information include sets of information such asdevice user name, type of a device being connected, name of contentsoutputted from the device (movie title, program title, file name, andthe like), an encoding scheme supported by the device, bit rate,information on whether or not a communication station and a device areready for information transmission therebetween, and information onwhether or not the device is currently used by any communicationstation.

The device user name and the type of a device being connected are setsof information by which the user can easily identify a plug in a device.These sets of information are used for the purpose of providing them tothe user before the user selects devices so that the user can easilyknow a device to be selected, showing the user what kind of devicescurrently displayed devices are, and other purposes.

The encoding scheme supported by the device and the bit rate are usedfor judging whether or not a content outputted from a device on thetransmitting side can be reproduced by a device on the receiving side,judging whether or not there remains a sufficient bandwidth to transmitthe content on a network path between communication stations, and otherpurposes.

The information on whether or not a communication station and a deviceare ready for information transmission therebetween is used for judgingwhether or not switching to the device is to be permitted. Further, theinformation on whether or not the device is currently used by anycommunication station is used for management of a control right for thedevice.

The device user name included in the plug information is not numericvalues or null character string, but a nickname for a device, which iseasy for the user to understand, such as “VCR manufactured by maker S”.For example, to enter the device user name of the device a 2300 beingconnected to the communication station B 2100, the user performscharacter string entering operation by using the user input section 2203of the controller B 2200. This operation is converted into a controlsignal by the controller control section 2202 and the control signal isoutputted from the control signal output section 2201. When the controlsignal input section 2107 of the communication station B 2100 receivesthis signal, the communication station control section 2109 analyses thereceived signal, converts it into a device user name such as characterstring, and stores the device user name as plug information in thecommunication station A's information storage section 1101. Note that,it is desirable that at the time of activating a communication stationfor the first time, registration of the device user name is performedsubsequent to connection of the device to the communication station.However, the registration may be performed at the other timing. Further,in the case where registration of the device user name has not beenperformed, it is conceivable to perform communications using a defaultvalue having been set during manufacture of the product. A conceivabledefault value is, for example, a number set corresponding to each of thevideo signal input sections, such as “Input 1”.

The type of a device, included in the plug information, is a set ofinformation made up of numeric values and character string by which theuser identify what the device is. This information may be specified by acharacter string, such as “VCR”, or may be a numeric value associationof which with the type of a device is uniquely determined among all ofthe communication stations (for example, numeric value 1 means “VCR”).This information, as with the device user name, is basically entered byusing the controller B 2200; however, it may be automatically acquiredby the communication station B 2100.

In the present embodiment, a video outputted from the communicationstation to the device and a video supplied from the device to thecommunication station are analog signals, and what converts the analogsignals into digital signals is a video encoding section, so that theencoding scheme and the bit rate, included in the plug information, aredetermined in accordance with performance of the video encoding section.For example, to acquire plug information of the device a 2300 beingconnected to the communication station B 2100, the communication stationcontrol section 2109 instructs the video encoding section 2111 to notifythe communication station control section 2109 of (i) an encoding schemeat the time of encoding a supplied video signal to digital signal and(ii) a value of bit rate, and stores the notified information as pluginformation, in the communication station B's information storagesection 2104.

(Wireless Connection Process)

Next, the following will describe (2) Scan, Join, Authentication,Association process in FIG. 3 (S105 through S108 and S156 through S159).This process is a process of executing MLME-Scan. request in a localcommunication station.

At any timing after completion of the initial setting, eachcommunication station performs a network establishment process. A startof the network establishment process may be triggered by some kind ofoperation performed by the user, or the network establishment processmay be automatically started by the communication station using its ownjudgment. The present embodiment describes a network establishmentprocess according to IEEE 802.11 network establishment process. What isused for network, not limited to a wireless network, may be a wirednetwork. Further, a communication protocol may be a protocol other thanIEEE 802.11.

A communication station which attempts connection to a network performsa step termed “Scan” to find networks which exist in the vicinity of thecommunication station. When the communication station performs the Scanstep, sets of information such as SSIDs from respective Access Points(hereinafter abbreviated as “APs”) each of which is a representativeterminal of each of the networks are sent back to the communicationstation.

The communication station, only to a network which complies withconditions, such as a condition that an AP has an SSID that is the sameas the SSID set to the communication station among APs found by the Scanstep, can perform a step termed “Join”. The Join step is a step ofrequesting the AP to permit a join of the communication station to thenetwork.

If the communication station is permitted to join the network, a messageindicating as such is sent back from the AP to the communicationstation. This allows the communication station to perform a step termed“Authentication”. In the present case, for data transmission afterencryption using the WEP, the AP checks whether or not a WEP key of theAP is the same as a WEP key of the communication station which attemptsconnection to the network. If the WEP keys are different from eachother, the communication station cannot be basically connected to thenetwork. Therefore, in the previously-described method, the WEP key ofthe communication station which attempts connection to the AP of thenetwork must be arranged so as to be the same as the WEP key of the AP.

At the end, the communication station performs a step termed“Association” for registering its own information with respect to theAP. At the point in time when this step has been completed, thecommunication station becomes ready for data transmission and receptionover the network.

The above-described process is a process corresponding to flowchartsillustrated in FIGS. 4 and 8.

Hereinafter, for communications between communication stations, usedaddresses are the following two addresses: MAC (Media Access Control)address and communication station address. The MAC address is an addressof a communication station which is used in Media Access Control layerof the OSI reference model, and the MAC address is used by a wirelesssection 1106 and a wireless section 2101 to specify a destinationstation for wireless data transmission and reception. The MAC address isassigned to each product during manufacture of products, and the MACaddress must be a unique value in the world. The communication stationaddress is an address determined in a layer higher than the MAC layerand is an address determined to identify communication stations, withoutconsideration of a discrepancy in the MAC layer, on such a network thatdata transmissions are performed through a plurality of MAC-layerprotocols (e.g. a network such that IEEE 802.11 is used for a MAC-layerprotocol in a wireless connection part, but Ethernet® is used for aMAC-layer protocol outside the wireless connection part in awired-connection part where connection to an external network isprovided). In the present embodiment, the communication station addressis used to specify a destination station for command transmission andreception in the communication station control section 1104 and thecommunication station control section 2109. FIG. 11 illustrates anexample of a packet structure. A packet 401 has a destination's MACaddress 402, a transmitting end's MAC address 403, a destination'scommunication station address 404, a transmitting end's communicationstation address 405, a command identifier 406, and a contentcorresponding to the command identifier 406.

(Device Information Collection)

Next, the following will describe (3) device information collectionprocess in FIG. 3.

The following process flow, on the video receiving side, corresponds toa flowchart illustrated in FIG. 5.

To designate a device from which a video is received, each communicationstation collects sets of information on all of communication stationsexisting on the network and devices connected to the communicationstations. A basic flow is as follows: a communication station whichwants to acquire information transmits a device information requestcommand to all the communication stations, and a communication stationwhich has received the command sends back its own information. Thefollowing will describe a process for the communication station A 1100on the video receiving side acquiring information on the communicationstation B 2100. The communication station control section 1104 instructsa wireless signal generation section 1103 to generate a wireless signal.In this case, this wireless signal includes (i) an identifier indicatinga device information request command and (ii) a communication stationaddress of the communication station A 1100 acquired from thecommunication station B's information storage section 2104. Further, asdestination addresses of the wireless signal specified are MAC address,communication station address, and an address such that the wirelesssignal is addressed to all the communication stations. The generatedwireless signal is transmitted through the wireless section 1106 (S111).

The wireless signal is received by the wireless section 2101 of thecommunication station B 2100, and when a wireless signal analyzingsection 2102 recognizes from the destination's MAC address that thewireless signal is addressed to the communication station B 2100, thewireless signal analyzing section 2102 further acquires the identifierindicating device information request command, the destination'scommunication station address, and the transmitting end's communicationstation address, all of which are included in the wireless signal, andnotifies the communication station control section 2109 of them. Whenthe communication station control section 2109 recognizes from theidentifier indicating device information request command and thedestination's communication station address that the device informationrequest command is addressed to the communication station B 2100, thecommunication station control section 2109 instructs a wireless signalgeneration section 2108 to generate (i) an identifier indicating aresponse to the device information request command and (ii) a wirelesssignal including information acquired from the communication station B'sinformation storage section 2104, and the generated identifier andwireless signal are transmitted through the wireless section 2101. Inthis case, conceivable sets of information included in the wirelesssignal are sets of information such as communication station B's MACaddress, communication station B's communication station address,communication station user name, all sets of plug information of thecommunication station B 2100, and whether or not the communicationstation B 2100 is a HC, described later, in the IEEE 802.11.

In S112 through S116, the wireless section 1106 of the communicationstation A 1100 receives the wireless signal, and when a wireless signalanalyzing section 1107 recognizes from the destination's MAC addressthat the wireless signal is addressed to the communication station A1100, the wireless signal analyzing section 1107 further acquires theidentifier indicating a response to the device information requestcommand, included in the wireless signal, and all the other sets ofinformation on the communication station B 2100, and notifies thecommunication station A 1100 of them. When the communication stationcontrol section 1104 recognizes from the identifier indicating aresponse to the device information request command and the destination'scommunication station address that the command is addressed to thecommunication station A 1100, the communication station control section1104 stores all the other sets of information on the communicationstation B 2100, notified by the wireless signal analyzing section 1107,in the form of a table in which the other sets of information areassociated with the communication station address of the communicationstation B 2100, in an other station's information storage section 1109(S115).

The above device information request command is transmitted so as to beaddressed to all the communication stations on the network, so that aresponse to the device information request command is made by all thecommunication stations on the network as well as the communicationstation B. Accordingly, the communication station A can acquire sets ofinformation on all the communication stations on the network and devicesconnected to the communication stations. In the present case, thecommunication station control section 1104 of the communication stationA 1100 cannot know whether or not responses to the device informationrequest command have been sent back from all the terminals on thenetwork, so that at the point in time when a given time has elapsed, thecommunication station control section 1104 determines that collection ofdevice information has completed, and ignores any response to the deviceinformation request command having been received after the point (S113).The above description has been given based on the process on the videoreceiving side. Also, on the video transmitting side, sets ofinformation on other communication stations and devices can be acquiredin the same process.

Note that, the above description has been given based on an embodimentin which each communication station collects all the sets of pluginformation on other communication stations. A method of switching withone action, as will be described later, allows each communicationstation to perform switching operation without knowing information onwhat kind of communication station other communication station is, orinformation on what kind of plug exists on each communication station.

Therefore, conceivable information that the communication station B 2100includes in the wireless signal of the response to the deviceinformation request command is both its own MAC address and its owncommunication station address, or either of them.

(Video Transmission Start)

Next, the following will describe (4) video transmission startingprocess in FIG. 3.

The following process flow, on the video receiving side, corresponds toa flowchart illustrated in FIG. 6, and the same process flow, on thevideo transmitting side, corresponds to a flowchart illustrated in FIG.9.

When sets of information on all the communication stations and deviceson the network are acquired, the communication station automaticallydetermines a combination of a communication station and a device whichis the other end to/from which a video is to be transmitted/received. Abasic flow is as follows: the communication station A 1100 checkswhether or not it has previously received a video from any of thecommunication stations (S121), and if having previously received a videofrom any of the communication stations, the communication station A 1100requests the most recently connected communication station among thecommunication stations to transmit a video (S124, S122). If not havingpreviously received a video from any of the communication stations, thecommunication station A 1100 determines the other end from which a videois to be received, in accordance with a particular rule (S123, S124).

The following will specifically describe a case where the communicationstation A 1100 on the video receiving side requests the communicationstation B 2100 to transmit a video. If the communication station A 1100has previously received a video from any of the communication stations,it is assumed that the communication station A 1100 stores, as sets ofinformation on other communication station from which a video isreceived, communication station address, MAC address, communicationstation user name, plug ID, plug information, and others of othercommunication station from which the communication station A 1100 hasreceived a video most recently, in the communication station A'sinformation storage section 1101. If the communication station A 1100has not received a video from any of the communication stations, acommunication station from which the communication station A 1100 hasreceived a video has disappeared from the network with an explicitlyperformed withdrawal process, or a given period has elapsed since thecommunication station A 1100 has received a video, it is assumed thatthese sets of information on other communication station from which avideo is received, are erased.

The following will describe specific examples when a communicationstation withdraws from the network with an explicitly performedwithdrawal process with reference to FIG. 1. In FIG. 1, assuming thatthe wireless station A 1100 is a video receiver, the display device 1400is a TV, and the controller A is a remote controller for the videoreceiver, conceivable specific examples when the communication stationwithdraws from the network with explicitly performed withdrawal processare the following two situations.

The first situation is when the user turns off the video receiver(communication station A 1100) with the remote controller (controller A1200) for the video receiver (communication station A 1100). It isconceivable that the user performs such an operation to finish viewing avideo through the video receiver (communication station A 1100). Whenthe communication station A 1100 receives a control signal from thecontroller A 1200, the communication station A 1100 transmits, via thewireless section A 1106, a wireless signal indicating withdrawal fromthe network.

The second situation is when the user turns off the TV (display device1400). In this case, it is assumed that the video receiver(communication station A 1100) has means which detects power-off of theTV (display device 1400) (not shown). It is conceivable that the userperforms such an operation to finish all video viewing on the TV(display device 1400). When the means not shown in the communicationstation A 1100 detects power-off of the display device, thecommunication station A 1100 sends out, via the wireless section A 1106,the wireless signal indicating withdrawal from the network.

The communication station control section 1104 of the communicationstation A 1100 checks whether or not the communication station A'sinformation storage section 1101 has stored therein the information onother communication station from which a video is received. If thisinformation has been stored therein, the communication station controlsection 1104 omits a process given as below and requests videotransmission with respect to other communication station specified by acommunication station address, MAC address, and plug ID all of which arestored in the communication station A's information storage section1101. If the information on other communication station from which avideo is received has not been stored therein, the communication stationcontrol section 1104 selects a combination of a communication stationand a device, which is the other end from which a video is to be newlyreceived, according to acquired sets of information on all thecommunication stations, having been previously stored in an otherstation's information storage section 2105, and requests the selectedcombination to transmit a video. A conceivable selection method is, forexample, a method of selecting a communication station which has the MACaddress being the lowest in number and selecting, from among devicesconnected to the thus selected communication station, a device specifiedby plug information having plug ID being the lowest in number.

(Video Transmission Request)

Note that, in either of the cases, i.e. the case when a device to beconnected is selected in accordance with the information on othercommunication station from which a video is received and the case when adevice to be connected is newly selected, the communication stationcontrol section 1104 refers to the previously acquired plug informationto judge whether or not a device of the plug information is available.If it is judged that the device is not available for some reason, it canbe considered that the device is unselected and another device isselected.

Conceivable conditions where a device is unselected are the followingconditions (1)-(4):

(1) A communication station and a device on the video transmitting sideare not ready for information transmissions therebetween (for the reasonthat they are not physically connected to each other, they are in areasbeyond the reach of radio waves, or steps for connection on the protocolare not completed);

(2) In a transmission path between a communication station on the videoreceiving side and a communication station on the video transmittingside, there is not enough bandwidth to transmit data outputted from aselected device (in the case where there is not enough transmissionbandwidth to share a network path for multiple data transmissions (aconceivable transmitting end is a communication station on the videoreceiving side, a communication station on the video transmitting side,or other communication station) since the network path has been alreadyused for another data transmission, or other case);

(3) The plug information indicates that the plug is in user; and

(4) A video outputted from a selected device cannot be reproduced on thevideo receiving side (in the case where a communication station on thereceiving side and the display device do not comply with an encodingscheme and a bit rate, or other case).

If one device is unselected, alternative device is selected. Conceivablealternative device selecting methods are the following methods (1) and(2):

(1) A plurality of sets of information on other communication stationfrom which a video is received are stored in advance and the sets ofinformation are referred to in reverse chronological order (if there isno information on other communication station from which a video isreceived, the selecting method is changed to the following method (2));and

(2) The MAC addresses or plug IDs are selected in ascending numericorder.

The above description has been given based on an example of anarrangement in which the communication station A 1100 on the videoreceiving side requests establishment of communications to thecommunication station B 2100 on the video transmitting side. However,the communication station B 2100 may request establishment ofcommunications to the communication station A 1100. The above.description has been given based on an example of an arrangement inwhich without user's explicit designation, some combination of acommunication station and a device is automatically selected. However, asystem in which no combination of a communication station and a deviceis selected until the user selects any combination is also conceivable.

Note that, the above description has been given based on a method inwhich the communication station on the video receiving side storestherein both addresses (communication station address and MAC address)and a plug ID of other communication station from which thecommunication station on the video receiving side has received a videomost recently. Another conceivable method is a method in which thecommunication station on the video receiving side stores therein onlyaddresses of other communication station from which the communicationstation on the video receiving side has received a video most recentlyand a communication station on the video transmitting side storestherein information corresponding to the plug ID. This informationmanagement method will be described later.

If one communication station decides other communication station fromwhich a video is received, it requests video transmission to the othercommunication station (S124). Assuming that in such a manner asdescribed previously, the communication station A 1100 has decided thecommunication station B 2100 as other communication station from whichthe communication station A 1100 receives a video, the following willspecifically describe a process when the communication station A 1100requests video transmission to the communication station B 2100. Thecommunication station control section 1104 of the communication stationA 1100 instructs the wireless signal generation section 1103 to generatea wireless signal. In the present case, the wireless signal includes anidentifier indicating that this wireless signal is a video transmissionrequest command, a communication station address of the communicationstation A 1100, a plug ID connected to a device selected as a devicefrom which the communication station A 1100 receives a video, and acommunication station address of a communication station connected tothe selected device. Further, the communication station control section1104 acquires a MAC address of the previously-selected communicationstation from the other station's information storage section 1109 anddesignates as a destination's MAC address of the wireless signal. Thegenerated wireless signal is transmitted through the wireless section1106.

The wireless signal is received by the wireless section 2101 of thecommunication station B 2100 (S162 in FIG. 9), and when the wirelesssignal analyzing section 2102 recognizes from the destination's MACaddress that the wireless signal is addressed to the communicationstation B 2100, the wireless signal analyzing section 2102 furtheracquires the identifier indicating the video transmission requestcommand, the destination's communication station address, the plug IDrequested video transmission, the communication station address of thewireless signal transmitting end, and others all of which are includedin the wireless signal, and notifies the communication station controlsection 2109 of them. When the communication station control section2109 recognizes, from the identifier indicating the video transmissionrequest command and the destination's communication station address,that the wireless signal is addressed to the communication station B2100 and what this command means, the communication station controlsection 2109 determines whether or not to permit video transmission fromthe device designated by the plug ID to the transmission requesting end(S164). For example, permission is determined on the following criteria:whether or not the device is in use; whether or not the device ispowered; or whether or not a video signal from the device is beingsupplied. Any of the criteria can be adopted for permissiondetermination.

In the present case, if necessary, plug information on the device towhich permission of video transmission is granted is updated (S166).Conceivable information in need of updating is information on whether ornot the device is being used, and a communication station address andMAC address of a communication station to which the device will transmita video.

As a result of determination, if the communication station controlsection 2109 does not permit video transmission, a wireless signal whichis a response to the video transmission request command is generated andtransmitted through the wireless section 2101 (S165). The presentembodiment assumes that all the communication stations specify inadvance sets of information each indicating the reason why videotransmission is not permitted, the information including a valueassociated with its meaning (For example, value 1 is associated with themeaning that “video transmission from the designated device is notpermitted since it is now in use”). Further, it is assumed that onevalue in the information means permission of video transmission. Such avalue is termed “response status”.

If another user on the video transmitting side is using the device a anddoes not want the permission of video transmission from the device a,the user on the video transmitting side performs an operation by meansof the user input section 2203 of the controller B 2200, which is acontroller for the communication station B 2100, thereby specifying assuch. Examples of this operation include “a push of ano-transmissions-from-the-device-a mode button”. The controller controlsection 2202 which has detected inputs from the user input section 2203generates a no-transmissions-mode setting signal and outputs thegenerated signal through the control signal output section 2201. Whenthe control signal input section 2107 of the communication station B2100 receives this signal, the communication station control section2109 detects that the received signal is the no-transmissions-modesetting signal, and updates plug information corresponding to thedesignated device among sets of plug information stored in thecommunication station B's information storage section 2104. Thereafter,when a video transmission request is made by another communicationstation, it is determined whether or not permission of videotransmission is granted, according to the thus updated plug information.Therefore, the video transmission request made to the user-designateddevice is refused.

Note that, in order not to permit video transmission, the communicationstation B 2100 may automatically select another plug in itself and sendback a wireless signal which is a response to the video transmissionrequest command, the wireless signal including (a) the response statusindicating permission of video transmission and (b) an ID of theautomatically selected plug.

In the present case, it is also conceivable that if the communicationstation B 2100 determines not to permit video transmission with respectto all the plugs in itself, it sends back a response status indicatingas such.

(Preparations for Video Transmission in Wireless Communications Zone)

Thereafter, at an arbitrary timing, the communication station on thevideo transmitting side starts video transmission (S167 through S172).

The following will describe a flow before the communication station B2100 starts transmission of a video supplied from the device a 2300, tothe communication station A 1100. In the present embodiment, acommunication-bands securing system according to the IEEE 802.11 isused, during video transmissions, to carry out the transmission at adetermined bit rate without interruptions by other communication stationin a wireless path. A contiguous group of data is termed “stream”, and atransmitting station or a receiving station of streams registers a bitrate and others required for transmission of each stream, in acommunication station termed “HC” (Hybrid Coordinator), performing bandmanagement. Then, with consideration given to all of the streams, the HCgrants a transmission right to each communication station. This allowseach communication station to carry out communications only during agrant duration of the transmission right. The HC coordinates atransmission right granting scheduling so that the streams are suitablytransmitted, whereby communication bands provided to each stream issecured.

When the communication station control section 2109 of the communicationstation B 2100 on the video transmitting side judges a readiness forvideo transmission in view of states of the device a 2300 and thecommunication station B 2100, the communication station control section2109 instructs the wireless signal generation section 2108 to generatean ADDTS-request wireless signal. Detailed descriptions of theADDTS-request wireless signal is omitted, but it is assumed that thissignal is based on the IEEE 802.11. This signal must include information(termed “stream information”) such as MAC addresses of the transmittingstation and the receiving station of streams and a bit rate required fortransmission of a data string to be transmitted as a stream. As a streamtransmitting station address, specified is a MAC address of thecommunication station B 2100, acquired by the communication station B'sinformation storage section 2104. As a stream receiving station address,specified is a MAC address of a communication station that is arecipient of a video, which is stored as plug information in the otherstation's information storage section 2105. Further, information such asa bit rate which is stored as plug information and notified by the videoencoding section is specified as stream information. Missing informationis complemented by appropriate values. In addition, the ADDTS-requestwireless signal must be addressed to the HC. Any one of communicationstations on the network is the HC and which communication station is theHC have been checked during collection of the previously-mentioned setsof communication station information, and a MAC address of the HC havingbeen obtained is specified. The generated ADDTS-request wireless signalis transmitted through the wireless section 2101. In the presentembodiment, the video transmitting end performs registration of thestream information with respect to the HC. Instead, the video receivingend may perform registration of the stream information.

When a communication station which is the HC receives the ADDTS-requestwireless signal, communications of wireless signals are carried outseveral times between the stream transmitting station and the HC andbetween the stream receiving station and the HC, in readiness for bandssecuring. Descriptions of this operation is omitted since it is based onthe IEEE 802.11 (S167).

After preparations for stream transmissions are made between the streamtransmitting station and the HC and between the stream receiving stationand the HC, the stream transmitting station triggers the HC to startgranting of the transmission right to the stream transmitting station.When the communication station control section 2109 of the communicationstation B 2100 completes the ADDTS process (S167), and detects areadiness for stream transmissions, the communication station controlsection 2109 instructs the control signal output section 2113 to outputa video output start signal to the device a 2300 (S168).

(Recording of Control Signal)

In the present case, to output the video output start signal to thedevice a 2300, the communication station B 2100 must store therein inadvance the video output start signal for the device a. In the presentembodiment, this signal is stored in the following manner.

After or before the connection of the device a 2300 to the communicationstation B 2100, the user brings both the controller B 2200 that is acontroller for the communication station B 2100 and the controller a1300 that is a controller for the device a 2300 to a location where thecontrol signal output sections 1301 and A2201 of the respectivecontrollers can supply control signals with respect to the controlsignal input section 2107 of the communication station B 2100. First,through the user input section 2203 of the controller B 2200, the userperforms an operation for starting recording of the video output startsignal and specifying the plug ID corresponding to a device for whichthe video output start signal is recorded. For example, this operationis to push a “Remote Control Learning Button” for specifying start ofthe recording and push a “Enter Button” for specifying the plug IDcorresponding to a device for which the video output start signal isrecorded. These functions may be integrated into one button. Thecontroller control section 2202 having detected the operation throughthe user input section 2203 causes the control signal output section2201 to output a control signal recording start signal and a plug-IDspecification signal.

When the control signal input section 2107 of the communication stationB 2100 detects receipt of these signals, the communication stationcontrol section 2109 enters into a video output start signal recordingmode. In this case, the user may be notified in some manner that thecommunication station control section 2109 has entered into the videooutput start signal recording mode. Examples of the notification includelightning-up of an LED provided on the communication station B 2100.

Next, the user performs an operation for starting output of a video fromthe device a 2300 through the user input section 1203 of the controllera 1300. For example, this operation is to push a “Power Button” and a“Play Button” when the device a 2300 is a VCR. The controller controlsection 1303 having detected the operation through the user inputsection 1203 causes the control signal output section 1301 to output thevideo output start signal.

When the control signal input section 2107 of the communication stationB 2100 detects receipt of the video output start signal during the videooutput start signal recording mode, the control signal input section2107 performs a process of converting the received signal into a signalwhich the communication station control section 2109 can store in thecommunication station B's information storage section 2104 (e.g. aprocess of sampling the control signal, if infrared signal, to convertit into a digital signal), and notifies the communication stationcontrol section 2109 of the video output start signal.

The communication station control section 2109 stores in thecommunication station B's information storage section 2104 the videooutput start signal notified by the control signal input section 2107 asplug information corresponding to the plug ID having been previouslyspecified by the controller B 2200.

Upon completion of the signal recording, the user notifies thecommunication station B 2100 of completion of the recording the videooutput start signal. Receipt of this signal causes the communicationstation control section 2109 to finish the video output start signalrecording mode and to complete the recording of the control signal fromthe controller a 1300.

Later, if the need for outputting the video output start signal to thedevice a 2300 arises, the communication station control section 2109should search plug IDs for the plug information of the device a 2300,extract the video output start signal from the plug information, andcause the control signal output section 2113 to output this signal.

Such an operation is performed to all the devices connected to thecommunication station B 2100, thereby allowing the communication stationB 2100 to output the video output start signal to all the devicesconnected to the communication station B 2100.

Note that, it is conceivable to ignore receipt of irrelevant signalsduring the video output start signal recording mode.

Note that, the above description has been given based on how the controlsignal for causing the device to start outputting a video is recorded.Also, other signal such as a control signal for stopping outputting avideo (corresponding to a stop button or the like on a remotecontroller) and a control signal for controlling a content(corresponding to a fast-forward button, rewind button, or the like on aremote controller) can be recorded in the same manner.

(Start of Video Output from Device)

Upon receipt of the video output start signal, the control signal inputsection 2304 of the device a 2300 analyzes the signal, and a devicecontrol section 2303 recognizes that the received signal is a videooutput start signal and then instructs a video generation section 2302to generate a video. The video generation section 2302 generates a videoand then transmits a video signal through the video signal outputsection 2301 to the video signal input section 2110 of the communicationstation B 2100.

From the event that the video signal input section 2110 of thecommunication station B 2100 has detected receipt of the video signalfrom the device a 2300 (S169, S170), the communication station controlsection 2109 judges that the communication station B 2100 has succeededin receiving the video signal. In the present case, the video encodingsection 2111 encodes the received video signal. The encoded video signalis stored in the video encoding section 2111 until actual transmissionof a wireless signal is completed (if the need for retransmission or thelike arises, until the retransmission is completed). A storage locationof the encoded video signal may be the communication station controlsection 2109. If the video signal input section 2110 of thecommunication station B 2100 receives no video signal upon expiry of agiven time period (timeout) after the control signal output section 2113outputs the video output start signal (S173), the communication stationcontrol section 2109 judges that receipt of the video signal has endedin failure.

When the communication station B 2100 has succeeded in receiving thevideo signal, the communication station control section 1104 instructsthe wireless signal generation section 2108 to generate a wirelesssignal including an identifier indicating a response to the videotransmission request command. In the present case, the wireless signalincludes information indicating that video transmission has beenpermitted and the device succeeded in video transmission, together withthe communication station address of the communication station B 2100,the plug ID permitted video transmission, and others. An MAC address ofa communication station which has requested video transmission isacquired from the other station's information storage section 2105 andis specified as a destination's MAC address of the wireless signal. Thegenerated wireless signal is transmitted through the wireless section2101 (S171).

When the communication station B 2100 has failed receiving the videosignal, the communication station control section 1104 instructs thewireless signal generation section 2108 to generate a wireless signalincluding an identifier indicating a response to the video transmissionrequest command. In the present case, the wireless signal includesinformation indicating that video transmission has been permitted, butreceipt of a video from the device has ended in failure, together withthe communication station address of the communication station B 2100, aplug ID permitted video transmission, and others. An MAC address of acommunication station which has requested video transmission is acquiredfrom the other station's information storage section 2105 and isspecified as a destination's MAC address of the wireless signal. Thegenerated wireless signal is transmitted through the wireless section2101 (S174).

In the present case, it is also conceivable that the communicationstation B 2100 retransmits the video output start signal a given numberof times until the communication station B 2100 succeeds in receivingthe video signal from the device a 2300, and sends back the response tothe video transmission request command in the end.

When a success or failure of receipt of the video signal is determined,the communication station control section 2109 requests the HC to starta grant of the transmission right. How the transmission right is grantedis based on the IEEE 802.11, so that detailed descriptions thereof isomitted.

In response to a request for starting a grant of the transmission rightfrom the communication station B 2100 which is a stream transmittingstation, the HC transmits a wireless signal indicating a grant of thetransmission right, addressing it to the MAC address of thecommunication station B 2100. This wireless signal includes informationon transmission right grant duration.

Under the condition that the communication station B 2100 has succeededin receiving the video signal, when the wireless section 2101 of thecommunication station B 2100 receives the wireless signal indicating agrant of the transmission right, the communication station controlsection 2109 is notified through the wireless signal analyzing section2102 that the transmission right has been granted. In this case, thecommunication station control section 2109 is also notified ofinformation on transmission right grant duration, included in thewireless signal. During this duration, the communication station controlsection 1104 supplies to the wireless signal generation section 1103 anencoded signal of the video signal stored in the video encoding section,by a given smaller amount thereof, and instructs the wireless signalgeneration section 1103 to generate a wireless signal including theextracted signal. In the present case, this wireless signal includes anidentifier indicating transmission of the video signal, and others sothat upon receipt of the wireless signal, the receiving end canrecognize that the wireless signal includes the video signal.Furthermore, the wireless signal includes the communication stationaddress of the communication station B 2100 and the plug ID of thedevice supplying the video signal. The destination's communicationstation address and the destination's MAC address of the wireless signalare acquired from the other station's information storage section 1109and set. This wireless signal is transmitted through the wirelesssection 2101 (S172).

Note that, under the condition that the communication station B 2100 hasfailed to receive the video signal, when the communication station B2100 is granted the transmission right, the communication station B 2100may generate a dummy video and transmit it to the receiving end. In thiscase, the communication station control section 2109 of thecommunication station B 2100 generates a dummy video signal, supplies anencoded signal of the dummy video signal by a given smaller amountthereof to the wireless signal generation section 1103, and instructsthe wireless signal generation section 1103 to generate a wirelesssignal including the supplied signal (S175).

Examples of the dummy video include a blue background. An encodingscheme, bit rate, and others for this video assumes to be the same asthose previously registered in the ADDTS process. It is conceivable thatinstead of the communication station control section 2109, the videoencoding section 2111 generates the dummy video. On the receiving end,this dummy video is received and displayed on the display device. Fromthe blue background video, the user can recognize a failure in receiptof the video.

Now, the video transmitting station side has reached a “B2” step in FIG.9.

(Video Reception Process)

The following will describe a process when the receiving end receivesthe response to the video transmission request command (corresponding toS125 and subsequent steps in FIG. 6). The wireless section 1106 of thecommunication station A 1100 receives the wireless signal, and when thewireless signal analyzing section 1107 recognizes from the destination'sMAC address that the wireless signal is addressed to the communicationstation A 1100, the wireless signal analyzing section 1107 furtheracquires the identifier which is a response to the video transmissionrequest command, the destination's communication station address, thecommunication station address of the communication station which is atransmitter of the wireless address, the plug ID which is a target forrequest of video transmission, the response status, the communicationstation address of a transmitter of the wireless signal, and others, allof which included in the wireless signal, and notifies the communicationstation control section 1104 of them. When the communication stationcontrol section 1104 recognizes, from the identifier which is a responseto the video transmission request command and the destination'scommunication station address, that the wireless signal is addressed tothe communication station A 1100 and what the command means. Thecommunication station control section 1104 interprets the responsestatus and instructs a video superimposing section 1105 to superimposeon the video signal a message corresponding to the response status. Thesuperimposed signal is supplied from the video signal output section1108 to the video signal input section 1402 of the display device 1400,and is displayed on the display section 1404 through the display devicecontrol section 1403 so that the signal is provided to the user (S130).In the present case, it is not limited to display of an error message,and it may be arranged so as to automatically request video transmissionto another communication station and device. The error message may beprovided to the user by displaying it with a character string or icon onthe display section 1404 of the display device 1400 which is connectedto the communication station A 1100 on the video receiving side, or byusing an LED or LCD provided to show the occurrence of error withrespect to the communication station A 1100.

If the response status is a value indicating that a permission of videotransmission has not been granted (S131), the communication station A1100 enters into a user's-input-waiting state. Note that, if no responseto the video transmission request command is sent back (S127), anothererror message is shown up with respect to the user. In this case, it ispreferable to display the error message which is easy for the user tounderstand that the request for video transmission has failed for thereason different from the reason when a permission of video transmissionhas not been granted. Example of the message includes “NO RESPONSE TOTHE WIRELESS SIGNAL IS SENT BACK.”

If the response status is a value indicating that a permission of videotransmission has been granted, the communication station A 1100 entersinto a video-reception-waiting state (S132), and the communicationstation A 1100 waits for transmission of the video.

If the communication station A 1100 cannot receive the wireless signalincluding the video signal for a given time period (S133), thecommunication station A 1100 informs the user that a permission of videotransmission has been granted, but the video signal has not beentransmitted (S136), and the communication station A 1100 enters into auser's-operation-waiting state. Now, the communication station A 1100has reached an “A3” step in FIG. 6.

The following will describe a process when the video has been receivedproperly. The wireless section 1106 of the communication station A 1100receives the wireless signal (S134). When the wireless signal analyzingsection 1107 recognizes from the destination's MAC address that thewireless signal is addressed to the communication station A 1100, thewireless signal analyzing section 1107 further acquires an identifierindicating inclusion of the video signal, a destination's communicationstation address, a communication station address of the transmittingend, the plug ID of the transmitting end, and the video signal itself,and notifies the communication station control section 1104 of them.When the communication station control section 1104 recognizes, from theidentifier indicating inclusion of the video signal and thedestination's communication station address, that the wireless signal isaddressed to the communication station A 1100 and the video signal hasbeen received, the communication station control section 1104 suppliesthis signal to the video decoding section 1110. The video decodingsection 1110 decodes the received video signal into a form that can bedisplayed on the display device 1400. In the present case, thecommunication station control section 1104 further searches the otherstation's information storage section 2105 using the communicationstation address of the transmitting end and the plug ID so as to acquiresets of information such as a communication station user name of thetransmitting end communication station and a device user name. If thesesets of information are necessary, the video superimposing section 1105superimposes the sets of information as images of characters or iconsupon the decoded video. Examples of the superimposed images includecharacter information such as a communication station user name of thevideo-transmitting-end communication station and a device user name. Thedecoded video signal is subjected to superimposing of the characterinformation or the like, and supplied through the video signal outputsection 1108 to the video signal input section 1402 of the displaydevice 1400.

The display device 1400 causes the display section 1404 to displaythereon the video signal supplied from the video signal input section1402, passing through the display device control section 1403 (S135).This allows the user to view the video transmitted from thecommunication station B 2100. Now, the communication station A 1100 hasreached an “A3” state in FIG. 6.

The above has described the process corresponding to flowchartsillustrated in FIGS. 6 and 9.

(Operation of Device by Means of Controller)

The following will describe a process when the user operates a device bymeans of a controller.

In the present embodiment, when the user operates the controller a 1300on the video receiving side, a control signal of the controller a 1300is transmitted to the device a 2300, whereby the user can operate thedevice a 2300. The following will describe a specific flow in this case.At an arbitrary timing after the stream transmitting station, the streamreceiving station, and the HC become ready for stream transmission, theuser performs an operation that the user wants through the user inputsection 1303 of the controller a 1300. Assuming the controller a 1300 isa remote controller for VCR, this operation is, for example, a push of afast-forward button. The following will describe a process of performinga fast-forward operation as an example of a process of transmittinguser's operation to a device. The controller control section 1303 havingdetected an operation through the user input section 1302 generates afast-forward start signal and outputs it through the control signaloutput section 1301. Note that, it is desirable that after the user isinformed that the stream transmitting station, the stream receivingstation, and the HC become ready for stream transmission, the useroperates the controller a 1300. However, if the user has performed anoperation of the controller a 1300 before they become ready for streamtransmission, a response such as an error message display may be made.If this error message display is difficult, a system may be constructedon the assumption that the without any response to the user's operation,the user can recognize, from display of no video, that his/her operationhas ended in failure, and the user performs the operation of thecontroller a 1300 again.

When receiving the fast-forward start signal, the control signal inputsection 1102 of the communication station A 1100 perform a process ofconverting the received signal into a signal that can be transmitted asa wireless signal (for example, if the control signal is an infraredsignal, the control signal is converted into a digital signal bysampling), and notifies the communication station control section 1104of the converted control signal. This converted control signal ishereinafter referred to as “post-conversion control signal”. Thecommunication station control section 1104 instructs the wireless signalgeneration section 1103 to generate a wireless signal including (i) anidentifier indicating inclusion of the post-conversion control signaland (ii) the post-conversion control signal which has been notified bythe control signal input section 1102. In the present case, the wirelesssignal includes a communication station address of the communicationstation A 1100, a communication station address of a communicationstation which is a video transmitting end, a plug ID of a device whichis a video transmitting end, and other information. As a destination'sMAC address of the wireless signal specified is an MAC address of acommunication station which is a video transmitting end. These sets ofinformation are acquired from the other station's information storagesection 2105.

When the wireless section 2101 of the communication station B 2100receives the wireless signal, and the wireless signal analyzing section2102 recognizes from the destination's MAC address that the wirelesssignal is addressed to the communication station B 2100, the wirelesssection 2101 further acquires an identifier indicating inclusion of thepost-conversion control signal, a destination's communication stationaddress, a plug ID requested video transmission, the post-conversioncontrol signal, a communication station address of the post-conversioncontrol signal transmitting end, and other information, and the wirelesssection 2101 notifies the communication station control section 2109 ofthem. When the communication station control section 2109 recognizes,from the identifier indicating inclusion of the post-conversion controlsignal, that the wireless signal includes the post-conversion controlsignal, the communication station control section 2109 instructs thecontrol signal output section 2117 corresponding to a device specifiedby the plug ID to output the post-conversion control signal notified bythe wireless signal analyzing section 2102. The control signal outputsection 2113 returns the post-conversion control signal to a signal thatcan be outputted as a control signal (for example, the sampled digitalsignal is converted back into an infrared signal), and the fast-forwardstart signal is outputted as the control signal.

When the control signal input section 2304 of the device a 2300 receivesthe control signal, the signal is analyzed, so that a device controlsection 2303 performs a fast-forward operation as specified by thecontrol signal, with respect to the entire device a 2300.

(Termination of Video Transmission)

Next, the following will describe (5) a video transmission terminationprocess in FIG. 3.

As to the following process flow, operations of the communicationstation A 1100 correspond to a flowchart illustrated in FIG. 7, andoperations of the communication station B 2100 correspond to a flowchartillustrated in FIG. 10.

For termination of video transmission during display of a video, theuser operates the user input section 1203 of the controller A 1200 whichis a controller of the communication station A 1100, so as to instructtermination of video transmission. Specifically, this operation is anoperation such as “a push of a Communication Station Power-Off button”provided on the controller A 1200.

When the controller control section 1204 detects the operation throughthe user input section 1203, the controller control section 1204instructs the control signal output section 1201 to output a videotransmission termination signal. When the video transmission terminationsignal is received by the control signal input section 1102 of thecommunication station A 1100, the communication station control section1104 knows that the user has requested termination of video transmission(S142).

Here, the communication station A instructs any communication stationsto/from which the communication station A transmits/receives a video toterminate video transmission. As an example of such a case, thefollowing will describe a process of instructing the communicationstation B to terminate video transmission.

The communication station control section 1104 of the communicationstation A instructs the wireless signal generation section 1103 togenerate a wireless signal including an identifier indicating a videotransmission termination command. In the present case, the wirelesssignal includes a communication station address and MAC address of thecommunication station B and a plug ID, acquired from the other station'sinformation storage section 1109. The generated wireless signal istransmitted through the wireless section 1106 (S144), and thecommunication station A enters into a wireless-signal-waiting state(S145).

When the communication station B 2100 successfully has received thewireless signal including the video transmission termination command(S182 in FIG. 10), the communication station B 2100 sends back anacknowledgement-of-receipt wireless signal (S 184). When receiving thisacknowledgement-of-receipt wireless signal (S147), the communicationstation A 1100 recognizes that a communication station A 1100'sintention to terminate video transmission has been accepted. Also, itcan be considered that if the communication station A 1100 receives noacknowledgement-of-receipt wireless signal for a given period of time(S146), the communication station A 1100 recognizes that the wirelesssignal including the video transmission termination command has not beensuccessfully received by the communication station B 2100, and performsa process of retransmitting the wireless signal including the videotransmission termination command, or the like process until thecommunication station A 1100 receives the acknowledgement-of-receiptwireless signal from the communication station B 2100 (S144).

The communication station A performs the above-described process withrespect to all the communication stations to/from which thecommunication station A transmits/receives a video.

When the communication station A 1100 has ended in the state ofreceiving no videos from any other communication stations, thecommunication station A 1100 may stop operations of unnecessary blocksunder control of the communication station control section 1104 forreduction of power consumption so as to enter into a standby state.However, as described previously, entering into a power-off state is notdesirable since when the communication station A 1100 enters into apower-off state, the communication station A 1100 cannot make a responseto any wireless signal transmitted from other device.

The wireless signal is received by the wireless section 2101 of thecommunication station B 2100 (S182), and when the wireless signalanalyzing section 2102 recognizes from the destination's MAC addressthat the wireless signal is addressed to the communication station B2100, the wireless signal analyzing section 2102 further acquires theidentifier indicating the video transmission termination command, thedestination's communication station address, the plug ID requestedtermination of video transmission, and other information, and notifiesthe communication station control section 2109 of them. When thecommunication station control section 2109 recognizes, from theidentifier indicating the video transmission termination command and thedestination's communication station address, that the wireless signal isaddressed to the communication station B 2100 and what this commandmeans, the communication station control section 2109 stops transmissionof a next and subsequent wireless signal including a video signal. Then,the communication station B 2100 informs the HC to release the bandssecured for the video transmission of which has been stopped. A detaileddescription of this process is omitted. However, this process is basedon a process termed “DELTES” specified by the IEEE 802.11e (S185). Uponcompletion of the DELTS process, the HC terminates the transmissionright grant to the specified-stream transmitting station, and ifnecessary, the HC assigns the bands used for the released steam, foranother stream transmission.

Before instructing stop of video transmission by means of the controllerA 1200, the user is supposed to perform, with respect to the device a2300 which is transmitting a video, an operation indicating that the useof the device a 2300 has ended, such as power-off operation, byoperating the controller a 1300. If such an operation is not performed,but termination of video transmission is instructed by means of thecontroller a 1200, the communication station B 2100 on the videotransmitting end may automatically perform a power-off operation of thedevice a 2300 or the like operation. For example, this can be realizedin such a manner that when the communication station B 2100 receives thewireless signal of the video transmission termination command from thecommunication station A 1100, the communication station control section2109 causes the control signal output section 2113 to output a power-offsignal with respect to the device a 2300 (S186).

It is conceived that this power-off signal is, as discussed in thedescription of (4) the video transmission starting process in FIG. 3, isrecorded in advance in a remote communication station. This power-offsignal is received by the control signal input section 2304 of thedevice a 2300, and is understood by the device control section 2303.Then, the device control section 2303 performs control operation such asa power-off operation of the device a 2300.

Further, the communication station control section 2109 upgrades sets ofplug information so that other communication station can use the devicewhich has transmitted a video until then (S188).

At this point in time, if the communication station B 2100 becomes inthe state of transmitting no videos to any other communication stations(S189), the communication station B 2100 may stop operations ofunnecessary blocks under control of the communication station controlsection 1104 for reduction of power consumption so as to enter into astandby state. However, as described previously, entering into apower-off state is not desirable since when the communication station B2100 enters into a power-off state, the communication station B 2100cannot make a response to any wireless signal transmitted from anotherdevice.

(Switch with One Action)

Next, the following will describe a process of switching between aplurality of devices which are connected to a plurality of remotecommunication stations, with one action (with a push of one button).

FIG. 12 illustrates an example of a system configuration. Eachcommunication station and devices connected to each communicationstation are extracted from the illustration in FIG. 1. A communicationstation A 101, a communication station B 102, and a communicationstation C 103 are connected to a network. To the communication station A101, a display device z 105 is connected through plugs 101 a and 101 b.Further, the communication station A 101 is controlled by a controller104. To the communication station B 102, a device a 106, a device b 107,and a device c 108 are connected through plugs 106 a and 106 b, plugs107 a and 107 b, and plugs 108 a and 108 b, respectively. Similarly, tothe communication station C 103, a device d 109, a device e 110, and adevice f 111 are connected through plugs 109 a and 109 b, plugs 110 aand 110 b, and plugs 111 a and 111 b, respectively.

The communication station A 101 is termed “local communication station”since the communication station A 101 is on the side where the userperforms its operation. The communication station B 102 and thecommunication station C 103 are termed “remote communication stations”since the user cannot directly operate them, but the user operate themthrough the local communication station.

On the display device, information from a device selected by the remotecommunication station is displayed.

The present embodiment assumes that the local communication station cancommunicate with any one of the remote communication stations, and as todevices connected to the remote communication station, the remotecommunication station, when receiving a switching command from the localcommunication station, switches between plugs in a fixed order.

Further, after a plug switching, if necessary, sets of data (bit rateand other data) having been communicated between the local communicationstation and the remote communication station are updated.

A switching command is used so that the local communication station canswitch between plugs used by the remote communication station. Theswitching command is transmitted from a controller operated by the user,and is transmitted via the local communication station to the remotecommunication station. After switching between plugs, the remotecommunication station transmits a response to the switching command.

The controller 104 may be allowed not only to transmit the switchingcommand (switching request), but also to control a selected contentproviding station or a device (such as communication station B 102, orthe device a 106, the device b 107, or the device c 108). Operationinformation may be set in advance in the controller, may be downloadedfrom each device, or may be arranged such that an operation signal isrecognized by the content providing station and a content requestingstation and converted into a form that can be recognized by the devices.How the devices are controlled with the controller is not specified bythe present invention.

The local communication station can transmit the switching command,without knowing states of the devices of the remote communicationstation and sets of information on the devices (plug ID and otherinformation). The remote communication station all judges whether or notswitching is possible.

FIG. 13 is a diagram including necessary functions taken out, divided,and collected from FIGS. 1 and 2, which are block diagrams ofcommunication stations, for easy illustration of the present embodiment.The same arrangement can be applied to the local communication stationand the remote communication station.

A communication section 201 is a processing section used forcommunications with a communication station and a controller. In thepresent embodiment, through this communication section 201,communications with the controller and the communication stations areperformed. The communication section 201 corresponds to the wirelesssection 1106 and the control signal input section 1102 in FIG. 1, andcorresponds to the wireless section 2102 and the control signal outputsection 2116 in FIG. 2.

An outgoing data generation section 202 converts sets of data andcommands into a form that can be transmitted by the communicationsection 201, and notifies the communication section 201 of them. Theoutgoing data generation section 202 corresponds to the wireless signalgeneration section 1103 and the communication station control section1104 in FIG. 1, and corresponds to the wireless signal generationsection 2108 and the communication station control section 2109 in FIG.2.

An incoming data analyzing section 203 identifies the data having beennotified by the communication section 201 or a plug section 204.Depending upon the type of data, the incoming data analyzing section 203notifies each processing section of the data or specifies how the datais to be processed to each processing section. The incoming dataanalyzing section 203 corresponds to the wireless signal analyzingsection 1107 and the communication station control section 1104 in FIG.1, and corresponds to the wireless signal analyzing section 2102 and thecommunication station control section 2109 in FIG. 2.

The plug section 204 is a connection port which connects a device. Theplug section 204 corresponds to the video signal output section 1108 inFIG. 1 and corresponds to the video signal input section 2110, the videosignal input section 2112, and the video signal input section 2114 inFIG. 2.

A device setting storage section 205 is a section which stores thereinsettings of devices, such as a device setting management table and aselection order management table illustrated in FIGS. 17 through 22. Thedevice setting storage section 205 corresponds to the communicationstation A's information storage section 1101 and the other station'sinformation storage section 1109 in FIG. 1 and corresponds to thecommunication station B's information storage section 2104 and otherstation's information storage section 2105 in FIG. 2.

A switching command processing section 206, in the local communicationstation, upon receipt of a switching command response “ALL PLUGSSWITCHED”, refers to various tables inside the device setting storagesection 205 to determine a remote communication station to communicatewith, under instruction from the incoming data analyzing section 203.Meanwhile, upon receipt of the switching command, the selection commandprocessing section 206, in the remote communication station, is notifiedof the switching command by the incoming data analyzing section 203, andrefers to various tables inside the device setting storage section 205to determine a plug to be selected. The selection command processingsection 206 corresponds to the communication station control section1104 in FIG. 1 and corresponds to the communication station controlsection 2109 in FIG. 2.

A plug selection section 207 switches to a plug determined by theswitching command processing section 206. The plug selection section 207corresponds to the communication station control section 1104 in FIG. 1and corresponds to the communication station control section 2109 andothers in FIG. 2.

A various commands processing section 208 is a processing section whichperforms processing of commands except for the switching command. Thevarious commands processing section 208 corresponds to the communicationcontrol section 1104 in FIG. 1 and corresponds to the communicationstation control section 2109 and others in FIG. 2.

A timer section 209 is used for determination of a timeout or the like.In the remote station, the timer section 209 is an unnecessaryprocessing section.

FIG. 14 illustrates a flowchart in the local communication station.

FIG. 15 illustrates a flowchart in the remote communication station.

FIG. 16 illustrates an order in which exchanges of data are carried outbetween the communication stations.

FIGS. 17 through 22 illustrate management tables of the localcommunication station and the remote communication station. The tablesillustrated in FIGS. 17 through 22 are examples of a device settingmanagement table 601 of the communication station A 101 (FIG. 17), aselection order management table 602 of the communication station A 101(FIG. 18), a device setting management table 603 of the communicationstation B 102 (FIG. 19), a selection order management table 604 of thecommunication station B 102 (FIG. 20), a device setting management table605 of the communication station C 103 (FIG. 21), and a selection ordermanagement table 606 of the communication station C 103 (FIG. 22). Thesetables are stored in the device setting storage section 205.

The device setting management table is a table for managing: (a) a plug(plug ID) currently used by a communication station; and (b) acommunication station (communication station address) being incommunication with the plug. The selection order management table is atable for managing an order for selecting the communication stationaddress or the plug ID (selection order, selection rule). In this table,the selection order is fixed and ascending order in the presentembodiment, and upon completion of selection of plugs from 1 to 3, theselection of plugs are ended.

FIGS. 23 and 24 illustrate examples of general views of controllers 711and 712, respectively. The controllers 711 and 712 correspond to thecontroller A 1200 and the controller a 1300 in FIG. 1, and correspondsto the controller B 2200 and others in FIG. 2.

A switching button 701 provides selection of an input plug of the remotecommunication station and provides selection of a device connected tothe remote communication station.

A power button 702 controls power of a communication station or devicethat can be controlled with a controller.

Various selections button 703 is necessary for calling up a menu forsetting functions of the display device and the local communicationstation and for selection and determination in the menu.

An adjustment button 704 is a button for adjusting a sound volume.

A channel button 705 is a button with which an intended televisionchannels to be called up on the display device can be directly selected.

An ascending-order switching button 706 is a button for selecting theorder in the order management table to an ascending order.

A descending-order switching button 707 is a button for selecting theorder in the order management table to a descending order.

Each button corresponds to the user input section 1203 or the like inFIG. 1.

The following will describe a flow of a packet between devices in FIG.16. The communication stations and the devices are arranged in the samemanner as in the system in FIG. 12.

Hereinafter, contents of the device setting management table are simplyrepresented by (Communication station name [selected plug ID, usedcommunication station address]). For example, when the selected plug IDis c in the communication station B 102 and the used communicationstation is A, they are represented by (B[c, A]). Further, when they arebeing cleared since there are no stations in communication, they arerepresented specially by (B[-, -]).

On the display device z connected to the communication station A 101,information from the device f connected to the communication station C103 is displayed (S501). In the present case, the device settingmanagement table of the communication station A 101 is (A[z, C]), andthe device setting management table of the communication station C 103is (C[f, A]). When the switching button on the controller is pushed(S502), the communication station A 101 transmits a switching command tothe communication station C 103. When receiving the switching command,the communication station C 103 refers to the device setting managementtable. In the device setting management table (C[f, A]), the selectedplug ID is “f” and the used communication station address is “A”, sothat the communication station C 103 refers to the selection ordermanagement table 606 to check what plug ID follows the plug ID “f”.

The communication station C 103 finds that the plug ID “f” is the lastplug ID in the selection management order table. Since a furtherswitching between plugs is impossible in the communication station C103, the communication station C 103 transmits a communication stopcommand to the device f, and transmits a response “ALL PLUGS SWITCHED”to the communication station A 101. Then, the communication station C103 clears the selection device setting management table (C[-, -]), andends communications with the communication station A 101 (S503).

Upon receipt of the response “ALL PLUGS SWITCHED”, the communicationstation A 101 updates the device setting management table (A[z, C]). Theused communication station address is an address of the communicationstation C 103. As seen from the selection order management table 602,there is no communication station to be selected next to thecommunication station C 103, so that the address of the communicationstation B 102 at the top of the selection order management table 602 isselected, and the device setting management table is updated (A[z, B]).Then the communication station A 101 transmits again the switchingcommand to the communication station B which is written in the usedcommunication station address (S504).

The communication station B 102 having received the switching commandrefers to the device setting management table. The device settingmanagement table is in the state of being cleared (B[-, -]), so that thecommunication station B 102 rewrites a field of the selected plug in thedevice setting management table, setting as the selected plug ID theplug ID “a” at the top of the selection order management table. Further,the communication station B 102 puts an address of the communicationstation A 101, which is a transmitting end of the switching command, inthe used communication station address (B[a, A]). Upon selection of theplug ID, the communication station B 102 transmits a communication startcommand to a device connected to a plug of the plug ID, and transmits aresponse “SWITCHING COMPLETED” to the communication station A 101(S505).

When the switching button on the controller is pushed again (S506), thelocal communication station A 101 refers to a field of the usedcommunication station address in the device setting management table(A[z, B]) and transmits the switching command to the remotecommunication station B 102. The remote communication station B 102having received the switching command refers to the device settingmanagement table. In the device setting management table (B[a, A]), theselected plug ID is “a”, and the used communication station address is“A”. Therefore, the remote communication station B 102 transmits acommunication stop command to a device having the plug ID “a”. Further,the remote communication station B 102 checks which plug ID follows theplug ID “a” in the selection order management table 604. The remotecommunication station B 102 can know that the plug ID “b” follows theplug ID “a”. Therefore, the remote communication station B 102 rewritesa field of the selected plug in the device setting management table,switching the selected plug from the device a to the device b (B[b, A])(S507). Upon selection of the plug ID, the remote communication stationB 102 transmits a communication start command to the device b connectedto the selected plug ID, and transmits a response “SWITCHING COMPLETED”to the local communication station A 101 (S508).

The above-described sequence allows the user to realize one-actionswitching of devices connected to the remote stations, withoutconsidering the communication stations and devices connected to thecommunication stations.

Referring to FIG. 14, the following will describe a process flow in thelocal communication station.

The local communication station, after its activation, collects sets ofcommunication station information and sets of device information fromany other communication stations (S201) (See the embodiment that hasdescribed the entire operation). Thereafter, the local communicationstation sets the device setting management table in the device settingstorage section 205 (S202). The local communication station waits forreceipt of a command from the communication section 201 (S203), andnotifies the incoming data analyzing section 203 of a received command.The incoming data analyzing section 203 determines the nature of thecommand. If the incoming data is a switching command, the localcommunication station refers to the device setting management table inthe device setting storage section 205, converts the incoming data intoa form that can be transmitted by the outgoing data generation section202, notifies the communication section 201 of the received data, andtransmits a switching command through the communication section 201 tothe remote communication station used (S206). Further, the localcommunication station informs the timer section 209 to notify when atimeout occurs. After the transmission of the switching command, eachprocessing section enters into a response-waiting state (S207). Uponreceipt of a response, the communication section 201 notifies theincoming data analyzing section 203 of the response. The incoming dataanalyzing section 203 determines the nature of the response. If theresponse is “ALL PLUGS SWITCHED” (S209), the incoming data analyzingsection 203 notifies the switching command processing section 206 of theresponse. The switching command processing section 206 refers to theselection order management table in the device setting storage section205, determines a communication station to be used next, and updates thedevice setting management table (S211). Thereafter, the localcommunication station causes the outgoing data generation 202 togenerate a switching command again, transmits the switching commandthrough the communication section 201 to the newly-determinedcommunication station to be used, and informs the timer section 209. Ifthe incoming response is “SWITCHING COMPLETED” and the localcommunication station must operate at a communication setting (e.g. bitrate) different from a communication setting for the device that thelocal communication station has previously used, the communicationsetting is changed (S212). Then, the local communication station returnsto a command-receipt waiting state (S203).

Further, if the local communication station receives a command otherthan the switching command, the various commands processing section 208performs a process corresponding to the received command (S205).

If the response is error, which means that the remote station has faileda device selection, the local communication station performs a processwhich is the same as a process performed when a timeout occurs.

The occurrence of a timeout of the response upon notification from thetimer section 209 (S208) implies that the communication station to whichthe switching command has been transmitted cannot perform communicationsfor some reason. Therefore, that communication station is skipped and acommunication station to be selected next is selected. In such a case,the switching command processing section 206 is informed as such. Theswitching command processing section 206 refers to the selection ordermanagement table in the device setting storage section 205, determines acommunication station to be used next, and updates the device settingmanagement table (S211). Thereafter, the outgoing data generationsection 202 generates a switching command again, and the communicationsection 201 transmits the switching command to the newly-determinedcommunication station to be used (S206).

Further, if the response is error or a timeout occurs, the localcommunication station may transmit the switching command to the samecommunication station again.

Referring to FIG. 15, the following will describe a process flow in theremote communication station.

Upon activation, the remote station waits for receipt of a command fromthe local communication station (S221).

Upon receipt of a command, the communication section 201 notifies theincoming data analyzing section 203 of the command to cause it todetermine the type of the command. If the received command is a commandother than the switching command, the incoming data analyzing section203 notifies the various commands processing section 208 of the commandother than the switching command to cause it to perform thecorresponding process, and the remote station returns to areceipt-waiting state (S223). If the received command is the switchingcommand, the incoming data analyzing section 203 notifies the switchingcommand processing section 206 of the switching command. The switchingcommand processing section 206 refers to the device setting managementtable and the order management table stored in the device settingstorage section 205 (S224). As a result of the reference to the tables,if switching between all plugs has been completed (S225), the switchingcommand processing section 206 clears the device setting managementtable (S229), informs the outgoing data generation section 202 togenerate a response “ALL PLUGS SWITCHED” and causes the communicationsection 201 to transmit the response to the local communication station(S230). Thereafter, the remote station ends communications with thelocal communication station, and the process is ended (S231). If thereis a plug to be switched (“NO” in S225), the switching commandprocessing section 206 determines whether or not selection of the plugis to be skipped (S232). If the plug is to be skipped, the process goesback to S224 to select a next plug. If it is determined that the plugskipping is not required, the switching command processing section 206updates the device setting management table (S226) and notifies the plugselection section 207 of a plug ID to be selected.

In the present case, the plug selection section 207 instructs the plugsection 204 to deactivate the plug having been previously used and toactivate a plug of the notified plug ID.

Further, the plug section 204 transmits, to a device corresponding tothe plug deactivation of which has been instructed, a control signal forcausing the device to stop video transmission (i.e. to make a contentunavailable for use). Examples of the control signal for stopping videotransmission include a signal for turning off the device and a signalfor causing the device to enter into a standby state. Further, ifpower-off of the device is not desired for the reason that it takes timeto activate the device or other reason, it is conceivable to transmit acontrol signal which merely stops video reproduction. This makes itpossible, when the user performs device switching without stopping videotransmission, to avoid the event where the device is kept turned on or avideo is transmitted continuously although there is no one who receivesa video.

Further, the plug section 204 transmits, to a device corresponding tothe plug activation of which has been instructed, a control signal forcausing the device to start video transmission (i.e. to make a contentavailable for use). With this arrangement, after the user performs thedevice switching operation, a video is transmitted automatically withoutany explicit operation for video transmission start, so that it ispossible for the user to view a video with a simpler operation. Aconceivable control signal for starting video transmission is a signalfor turning on the device. Further, as to a device that cannot startvideo transmission with power-on operation only (for example, a DVDplayer), it is conceivable to transmit, after transmission of a signalwhich turns on the device, a signal for starting video reproduction.

It is conceivable that these control signals for start of videotransmission and for stop of video transmission are recorded in advanceby the remote communication station in the same manner as described inthe explanation of the (4) video transmission starting process in FIG.3.

Also, in view of the case where the control signal has been alreadytransmitted to the device by the user, it is conceivable that afterchecking whether or not video transmission from the device is beingperformed, the remote station transmits a control signal for start ofvideo transmission or stop of video transmission. As to power-on andpower-off, the device may perform toggle operation with one controlsignal (operation that upon receipt of the control signal when thedevice is powered on, the device is powered off, and upon receipt of thecontrol signal when the device is powered off, the device is poweredon), so that this method is especially effective.

Examples of conditions for skipping selection of a plug include thefollowing (1) through (3). Note that, information necessary for judgmentof these conditions is assumed to be stored as plug information.

(1) The remote communication station and the device are not ready forinformation transmissions therebetween (for the reason that they are notphysically connected to each other, they are in areas beyond the reachof radio waves, or steps for connection on the protocol are notcompleted).

(2) In a transmission path between the local communication station andthe remote communication station, there is not enough bandwidth totransmit data outputted from a device connected to the selected plug (inthe case where there is not enough transmission bandwidth to share anetwork path for multiple data transmissions (a conceivable transmittingend of the data is the local communication station, the remotecommunication station, or other communication station) since the networkpath has been already used for another data transmission, or othercase); and

(3) The plug information indicates that the plug is in use.

Further, the present embodiment may be arranged such that if thecondition for skipping is met, the remote station notifies the user assuch, without skipping selection of a plug, and waits for a responsefrom the user. For example, if the device is not physically connected, aconceivable notification is to transmit a blue background image and todisplay an error message.

Further, the remote station notifies the outgoing data generationsection 202 and causes it to generate a response “SWITCHING COMPLETED”.Then, the remote station causes the communication section 201 totransmit the response to the local communication station (S227).Further, if the remote station must operate at a communication setting(e.g. bit rate) different from a communication setting for the devicethat the remote communication station has previously used, thecommunication setting is changed (S228). Then, each processing sectionreturns to a receipt-waiting state (S221).

(Selection Order in Order Management Table)

In the present embodiment, upon receipt of the switching command, aremote receiving station selects a plug ID to be selected next in theselection order management table, and selection of the plug ID inascending order has been taken as an example. An order in which the plugID is selected in the order management table is not necessarily anascending order, and the plug ID in the selection order management tablemay be selected in descending order. In this case, take a selectionorder management table 801 in FIG. 25 as an example. If the devicesetting management table is being cleared, a plug ID 801 c at the bottomof the order management table is first selected.

Each time the remote receiving station receives the switching command,the plug ID is selected in the following order: 801 b and 801 a. Whenthe remote receiving station has received the switching command aftercompletion of selection of all the plug IDs, the remote receivingstation selects no plug and clears the device setting management table,and transmits a response “ALL PLUGS SWITCHED” to the local communicationstation. This enables the same operation as that in the aboveembodiment.

Further, the plug ID may be selected at random, not in ascending orderand descending order. In this case, take a selection order managementtable 803 in FIG. 26 as an example. A selected bit table includingselected bits 803 a, 803 b, and 803 c is added to the selectionmanagement table. When a plug ID is selected, the corresponding selectedbit is set (803 b). If all the selected bits are set upon receipt of theswitching command, the remote communication station transmits a response“ALL PLUGS SWITCHED” to the local communication station, and theselected bits are cleared. This enables the same operation as that inthe above embodiment.

The above description has been given based on the plug ID. However, theused communication station address is also selected in the same manner.

(How to Set a Management Table)

The present embodiment assumes that the selection order management tableis, but not necessarily, fixed. The selection order may be determined bythe user or at random (FIG. 27) (802). However, in either case, acertain plug must be included at least once in the selection order.

Further, if the selection order management table is generated based on avalue assigned to each device, the value not varying in a fluid manner,a pair of devices can be selected in a given order.

For example, it is conceivable that the selection order managementtable, which is referred to by a content selection requesting stationfor transmission of the switching command, is created based on MACaddresses of the respective communication stations, having been acquiredin advance during (3) the device information collection process in FIG.3.

The MAC address is a unique number in the world to be assigned to eachdevice and a value of the MAC address does not vary. The MAC address isa value expressed by twelve-digit numbers in hexadecimal notation. Forexample, let that the MAC address of the communication station A is“CBA987654321” (hexadecimal) and the MAC address of the communicationstation B is “DCBA98765432” (hexadecimal). If the selection ordermanagement table is always created including an order in which an MACaddress having a lower value is selected first, the communicationstation A is selected before the communication station B.

This always provides a given selection order as long as thecommunication stations included in the selection order management do notchange. The MAC address is not varied by power-off or the like event ofthe communication station, so that this effect lasts permanently.

Further, in the event when a new communication station is added to anetwork and when an existing communication station is removed from anetwork, there occurs changes of an order associated with suchcommunication stations. However, a relative selection order associatedwith the other communication stations does not change. This minimizeschanges of the selection order.

In the same manner, the content providing station can create theselection order management table, which is referred to for plugselection upon receipt of the switching command.

For example, if the content providing station and the device areconnected through IEEE 1394, the selection order management table iscreated based on EUI-64 (Extended Unique Identifier, 64 bits) specifiedby IEEE 1394. The EUI-64 is a unique number in the world to be assignedto each IEEE 1394 device and a value of the EUI-64 does not vary.Therefore, the EUI-64 can be used in the same manner as the MAC addressdescribed earlier. In this case, it is conceivable that the contentproviding station collects EUI-64s in advance from the respectivedevices during (1) the initial setting process or the other process inFIG. 3. Note that, the above can be realized by another value if thevalue does not vary in a fluid manner and is only one value that can beassigned to one device.

It has been assumed that the device setting management table manages onecommunication station and one plug. However, the device settingmanagement table may manage a plurality of communication stations and aplurality of plugs. For example, the table may be arranged so as to showthat the plug a is used by the communication station A and the plug b isused by the communication station C 103 (FIG. 28) (804).

Further, the present invention may be arranged such that differentcommunication stations can use a device that is connected to the sameplug (FIG. 29) (805).

The present invention may be arranged such that after power-off or thelike operation of the communication station, when power to thecommunication station is again turned on, the communication station canreturn to the connection to a content which is the same as a previouscontent before the power-off.

Descriptions of the (4) video transmission starting process in FIG. 3include how the communication station on the video receiving sidemanages both the communication station address and the plug ID. If thesame process is applied to the present embodiment, the device settingmanagement table of the local communication station and the devicesetting management table of the remote communication station are storedeven after power-off, and the following process is performed.

To return to the connection to the content, the local communicationstation transmits a “connection return command” to a communicationstation currently designated in the device setting management table ofthe local communication station. Normally, upon receipt of the deviceswitching command, the remote communication station selects, for startof content transmission, a device designated in the selection ordermanagement table, the device following a device currently designated inthe device setting management table. On the other hand, upon receipt ofthe connection return command, the remote communication station selectsa device currently designated in the device setting management table,for start of content transmission. This allows the local communicationstation to return to the connection to the last content that the localcommunication station has received, whereby the local communicationstation can receive the same content.

Further, if the communication station or device designated in a certainentry of the stored device setting management table has removed from thenetwork after explicitly having performed a removal process, or if agiven period of time has elapsed since completion of the lastcommunication, it is conceivable to erase the entry.

In the present embodiment, an arrangement in which only the displaydevice z 105 is connected to the local communication station 101 in FIG.12 is taken as an example. However, a plurality of display devices maybe connected to the local communication station 101.

In this case, the device setting management table (in FIG. 17) in thelocal communication station should manage the selected plug ID and theused communication station address, as normally managed. The devicesetting management table (in FIG. 19) in the remote communicationstation needs, in addition to a currently used plug (selected plug ID)and a communication station using the currently used plug (usedcommunication station address), a plug ID of a display device using thecurrently used plug.

As an example taken is the following case: the communication station Ais connected to display devices z1 and z2, the display device z1 (plugID=z1) is in communication with a device a (plug ID=a) connected to thecommunication station B, and the display device z2 (plug ID=z2) is incommunication with a device b (plug ID=b) connected to the communicationstation C. FIG. 30 illustrates a device setting management table of thecommunication station A in this case. FIG. 31 illustrates a devicesetting management table of the communication station B in this case.FIG. 32 illustrates a device setting management table of thecommunication station C in this case.

Further, in the case where the display device z1 connected to thecommunication station A is in communication with the device a (plugID=a) connected to the communication station B, and the display devicez2 connected to the communication station A is in communication withanother device b (plug ID=b) connected to the communication station B,FIG. 33 illustrates a device setting management table of thecommunication station A, and FIG. 34 illustrates a device settingmanagement table of the communication station B.

In this case, when the switching command is transmitted from thecommunication station A to the communication station B, thecommunication station B cannot determine one entry in its own devicesetting management table only from a communication station address ofthe switching command transmitting end. That is, the communicationstation B cannot determine a plug targeted for switching. Therefore, thecommunication station A must transmit the switching command includinginformation on which display device the switching command correspondsto. For example, if the communication station A transmits, to thecommunication station B, a wireless signal for the switching commandincluding a newly provided field containing a plug ID of a displaydevice which is targeted by the switching command, the communicationstation B can determine one entry in the device setting management tablefrom both a value in the field and a communication station address ofthe switching command transmitting end.

Meanwhile, the communication station B must send back a response to theswitching command, to the communication station A, the responseincluding information on which display device the response to theswitching command corresponds to, so that the communication station Acan determine which display device the response to the switching commandcorresponds to. Similarly, in this case, the communication station Bshould transmit, to the communication station A, a packet for theresponse to the switching command including a newly provided fieldcontaining a plug ID of a display device which is targeted by theresponse to the switching command.

(Switching Command and Response)

In the foregoing embodiment, the local communication station transmitsthe switching command without knowing a status of the remotecommunication station. However, the local communication station mayacquire information on the remote communication station (informationsuch as which plug ID the remote communication information is connectedto), generate a switching command based on the information, and directlyperform control of device switching.

Further, the present invention may be arranged such that the remotecommunication station transmits a switching response includinginformation from which the user can determine a device itself and acontent outputted from the device, such as a device user name of aselected device, a type of a selected device, and a name of a contentoutputted from a selected device (movie title, program title, file name,or the like), so that the local communication station, the displaydevice, or the like can offer the information to the user. This makes iteasier for the user to understand what a currently selected device andcontent is.

Still further, the present invention may be arranged such that theremote communication station transmits a switching response includinginformation, from which a device itself and a content outputted from thedevice can be determined, on a device following a currently selecteddevice in the selection order management table, so that the remotecommunication station, the display device, or the like can offer theinformation to the user. This makes it easier for the user to know whatkind of device and content are to be selected when the user performs anext switching operation, thus making it easier for the user to select adevice and a content that the user wants.

Note that, under a circumstance where there are a plurality of remotecommunication stations that can be selected by the local communicationstation, when a selected device is a device positioned at the bottom ofthe selection order management table of a first remote communicationstation, the first remote communication station should transmit aswitching response including information to a device positioned at thetop of the selection order management table of a second remotecommunication station. In such a case, it is conceivable that the firstremote communication station is provided with means which inquires, tothe second remote communication station, about information from whichthe device itself and content outputted from the device can bedetermined, and the first remote communication station transmits, to thelocal communication station, the switching response includinginformation acquired by the inquiry of the first remote communicationstation.

Yet further, the present invention may be arranged such that the remotecommunication station transmits a switching response includinginformation, from which a device itself and a content outputted from thedevice can be determined, on a device followed by the currently selecteddevice in the selection order management table, so that the localcommunication station, the display device, or the like can offer theinformation to the user. Even if a switching operation in descendingorder is provided, this makes it easier for the user to know what kindof device and content are to be selected when the user performs a nextswitching operation, thus making it easier for the user to select adevice and a content that the user wants.

Note that, under a circumstance where there are a plurality of remotecommunication stations that can be selected by the local communicationstation, when a selected device is a device positioned at the top of theselection order management table of a first remote communicationstation, the first remote communication station should transmit aswitching response including information to a device positioned at thebottom of the selection order management table of a second remotecommunication station. In such a case, it is conceivable that the firstremote communication station is provided with means which inquires, tothe second remote communication station, about information from whichthe device itself and content outputted from the device can bedetermined, and the first remote communication station transmits, to thelocal communication station, the switching response includinginformation acquired by the inquiry of the first remote communicationstation.

The present invention may be arranged such that the remote communicationstation transmits a switching response including information, from whicha device itself and content outputted from the device can be determined,on any devices that can be selected from among devices connected to theremote communication station, so that the local communication station,the display device, or the like can offer the information to the user.This makes it possible for the user to know how many times the usershould perform switching operation to select a device and a content thatthe user wants, thus making it easier for the user to select a deviceand a content that the user wants.

Note that, under a circumstance where there are a plurality of remotecommunication stations that can be selected by the local communicationstation, it is conceivable that a first remote communication station isprovided with means which inquires, to all the other remotecommunication stations, about information on any devices that can beselected from among devices connected to the remote communicationstations, and the first remote communication station transmits, to thelocal communication station, the switching response includinginformation acquired by the inquiry.

(Controller's Target for Communication)

The present embodiment has described a case where a connection patternbetween the controller and the communication station is different from aconnection patter between the communication stations. However, aconnection pattern between the controller and the communication stationmay be the same as a connection patter between the communicationstations. In this case, the communication station should support onlyone connection pattern. With this arrangement, an advantageous effectsuch as reduction in manufacture cost is expected.

Further, the present invention assumes a system in which a transmittabledistance in a scheme of communications between the local communicationstation and the remote communication station is longer than that in ascheme of communications between the controller and the localcommunication station. For example, communications between thecontroller and the local communication station is carried out throughinfrared light, whereas communications between the local communicationstation and the remote communication station are wirelessly carried outby using 2.4 GHz or 5 GHz band. In such a case, if a connection patternbetween the controller and the local communication station is the sameas a connection pattern between the local communication station and theremote communication station, communications between the localcommunication station and the remote communication station arewirelessly carried out. This allows the user to operate the localcommunication station at a location distant from the local communicationstation.

The present embodiment has described only the case where the localcommunication station performs switching of a content to be displayedthereon. The local communication station may perform switching of acontent transmitted to a communication station other than the localcommunication station. In this case, it is conceivable that the localcommunication station transmits, to the remote communication station,the switching command including an address of a communication stationwhich the local communication wants to display a content thereon.

Further, the controller controls, through the local communicationstation, other communication station. However, the present invention maybe arranged such that the controller can directly control acommunication station other than the local communication station. Forexample, if communications between the controller and all thecommunication stations is carried out by using the same radio frequencybands and the same communication station protocol, controller's directcontrol of a communication station other than the local communicationstation can be realized. Further, the controller may be integrated intothe communication station, the display device, the device, and the like.

(Structure of Controller)

A typical display device in current use needs an “input switching”operation for selection of external connection devices for display. Thisis, for example, an “input switching” operation of a television. Withthis operation, the user can select a device that the user wants fordisplay from among a plurality of external devices (such as VTR andDVD).

In the present embodiment, if the local communication station isconnected to the display device, as such an external connection device,the user performs an operation of selecting external connection devicesand an operation of selecting devices connected to the localcommunication station via the remote communication station, by usingdifferent controllers.

Note that, a device switching method in the present invention isapplicable to an apparatus being the display device and localcommunication station combined into one unit (hereinafter referred to as“integral-type apparatus”). In this case, if the integral-type apparatusis arranged such that the use of a controller for the integral-typeapparatus enables both the operation of switching external connectiondevices and the operation of switching devices connected via the remotecommunication station, the user can perform both of the switchingoperations with a single controller.

Further, it is also possible to arrange such that the use of a singlebutton provided on the controller for the integral-type apparatus(hereinafter referred to as “dual-purpose switching button” enables theoperation of switching external connection devices and the operation ofswitching devices connected via the remote communication station.

User's push of the dual-purpose switching button provided on thecontroller for the integral-type apparatus is conveyed to theintegral-type apparatus. In the present case, the integral-typeapparatus performs the following processes:

(Process 1) If a device other than the local communication station iscurrently being selected as an external connection device of theintegral-type apparatus, switching between external connection devicesis carried out. Here, as in the case of a conventional television,switching between input terminals provided to the display device iscarried out in sequence.

(Process 2) If the local communication station is currently beingselected as an external connection device of the integral-typeapparatus, switching between devices connected to the localcommunication station via the remote communication station is carriedout in the process as described previously.

As to all the communication stations, each time the integral-typeapparatus has received a response “ALL PLUGS SWITCHED” from eachcommunication station, the integral-type apparatus selects an externalconnection device to be selected next to the local communicationstation.

Note that, an arrangement in which the local communication stationoutputs a switching control signal to the display device also realizesthe same operation as that described above.

User's push of a switching button provided on the controller for thelocal communication station is conveyed to the local communicationstation. In the present case, the local communication station performsthe following processes:

(Process 1) If a device other than the local communication station iscurrently being selected as an external connection device of the displaydevice, the local communication station outputs a switching controlsignal to the display device.

(Process 2) If the local communication station is currently beingselected as an external connection device of the display device,switching between devices connected to the local communication stationvia the remote communication station is carried out in the process asdescribed previously.

As to all the communication stations, each time the local communicationstation has received a response “ALL PLUGS SWITCHED” from eachcommunication station, the local communication station outputs aswitching control signal to the display device.

For the foregoing processes, the local communication station must judgewhether, as an external connection device of the display device, thelocal communication station or the other device is selected. Assumingthat the local communication station acquires in advance informationabout how many external communication devices are connected to thedisplay device and how manieth device the local communication station isto be connected to the display device, the above judgment is carried outin the following manner.

Assumes that at first, the first external connection device connected tothe display device is selected. The local communication station comparesthe number of times it has outputted the switching control signal to thedisplay device with information about how manieth device the localcommunication station is to be connected to the display device, therebyfirst knowing a timing when the local communication station is selected.Thereafter, the local communication station knows that the localcommunication station is selected again when outputting the switchingcontrol signal to the display device the number of times correspondingto the number of external connection devices connected to the displaydevice.

Conceivable approaches for the local communication station acquiringinformation about how many external connection devices are connected tothe display device and how manieth device the local communicationstation is to be connected to the display device, are that the userenters the information into the local communication station in advanceand that the local communication station and the display devicecommunicates some signal with each other for acquiring of theinformation.

A conceivable specific example of the foregoing arrangement is that thedisplay device is a conventional television, the local communicationstation stores therein an infrared remote control signal for televisioninput switching, and television input switching is controlled by thesignal.

Further, if the local communication station has a function of inquiringto the display device about whether or not the local communicationstation is currently selected as an external connection device, theforegoing process can be realized more easily. In this case, at the timewhen switching operation is performed with a controller for the localcommunication station, the local communication station should inquire tothe display device about whether or not the local communication stationis currently selected as an external connection device and perform theforegoing Process 1 or Process 2 depending upon a response to theinquiry.

Note that, the present invention may be arranged such that the localcommunication station outputs a control signal other than an externaldevice switching control signal with the user's operation using acontroller for the local communication station. With this arrangement,it is possible for the user to carry out various control operations withrespect to the display device only with an operation of the controllerfor the local communication station.

The arrangement in which the local communication station outputs acontrol signal to the display device has been described above. However,on the other hand, an arrangement in which the display device outputs acontrol signal to the local communication station can realize the same.

(Structure of the Communication Section 201)

The communication section 201 in FIG. 13 may be wireless or wired.Further, any protocol of the communication section 201 may be adopted.For example, for wireless communications, radio waves in 2.4 GHz band, 5GHz band, or UWB (Ultra Wide Band), or light such as infrared light maybe used in a physical layer. For wired communications, analog connectionor digital connection such as IEEE 1394 may be adopted. Further, aprotocol of the MAC layer may be wireless LAN (IEEE 802.11) or the like.Still further, the present invention may be arranged so as to include aplurality of communication sections 201. In this case, eachcommunication section may use a different connection scheme.

In the above embodiment, with a single button, the plug ID connected tothe remote communication station is selected from the order managementtable in ascending order or descending order. However, devices may beselected with two buttons: a button 706 for device selection inascending order and a button 707 for device selection in descendingorder. In this case, in the local communication station, the switchingcommand processing section 206 causes the outgoing data generationsection 202 to attach, to the switching command, information from whichwhether ascending order or descending order can be determined, andcauses the communication section 201 to transmit the switching commandattached with the information. Meanwhile, in the remote receptionstation, the communication section 201 notifies the incoming dataanalyzing section 203 of the command, and the incoming data analyzingsection 203 notifies the switching command processing section 206 ofascending order or descending order. The switching command processingsection 206 should use both the ascending order algorithm and thedescending order algorithm described in the foregoing embodiment, forreference to the order management table. A flow of other steps areomitted since it is the same as the foregoing flow. With thisarrangement, two buttons allow a convenient switching between ascendingorder and descending order.

The following will describe an example of a process flow to obtain astate where the user gets to view a video, with reference to FIG. 1 andFIG. 2. The following description is just one example, and a method ofcontrolling devices with a controller is not limited by the presentinvention.

Note that, the following example assumes that the communication stationA 1100 is a video receiver, the display device 1400 is a television set,the communication station B 2100 is a video transmitter, the device a2300 is a VCR, the device b 2400 is a CS tuner, and the device c 2500 isa hard disk recorder. Further, the following example assumes that thecontroller A 1200 is a remote controller for the video receiver, thecontroller a 1300 is a remote controller for the VCR, and the user viewsthe display device 1400 while operating the remote controller for thevideo receiver (controller A 1200) and the remote controller for the VCR(controller a 1300). Further, the following arrangement is not shown,but the user has a remote controller for the CS tuner and a remotecontroller for the hard disk recorder in hand, in addition to the remotecontroller for the VCR (controller a 1300).

The user turns on the video receiver (communication station A 1100) andthe video transmitter (communication station B 2100) so that wirelesscommunications are possible between the video receiver and the videotransmitter. Thereafter, the user turns on the television set (displaydevice 1400). This operation may be carried out by user's directoperation or by the remote controller for the television set (displaydevice 1400) (not shown). Thereafter, the user operates the remotecontroller for the video receiver (controller a 1300) to select a devicefrom which the user wants to view a video from among the VCR (device a2300), the CS tuner (device b 2400), and the hard disk recorder (devicec 2500), all of which are connected to the video transmitter(communication station B 2100). This operation is to push a switchingbutton on the remote controller for the video receiver (controller a1300). Detailed descriptions of the switching process are omitted sincethey have been already given.

Here, it is assumed that switching between the devices is carried out inthe following order: VTR (device a 2300), CS tuner (device b 2400), andhard disk recorder (device c 2500). Therefore, under the circumstancewhere the currently selected device is the VTR (device a 2300), forselection of the hard disk recorder (device c 2500), the user shouldpush the switching button on the remote controller for the videoreceiver (controller a 1300) twice.

After having switched to a device that the user wants, the user operatesthe device itself with a remote controller for the device. For example,after having switched to the VCR (device a 2300), the user picks up theremote controller for the VCR (controller a 1300) to operate the VCRwith it. Here, when the user wants to play a tape on the VCR, the userpushes a play button on the remote controller for the VCR (controller a1300). An infrared signal from the remote controller is converted into awireless signal by the video receiver (communication station A 1100),and the wireless signal is transmitted to the video transmitter(communication station B 2100) to control the VCR (device a 2300). Withthis arrangement, a video signal from the VCR (device a 2300) isconverted into a wireless signal by the video transmitter (communicationstation B 2100), the wireless signal is transmitted to the videoreceiver (communication station A 1100) to display video on thetelevision (display device 1400).

Further, the CS tuner (device b 2400) is operated in the same manner asthe above case. After the user switches to the CS tuner (device b 2400)with the remote controller for the video receiver (controller A 1200),the user picks up the remote controller for the CS tuner (not shown) tooperate the CS tuner with it. Here, when the user wants to turn on theCS tuner, the user pushes a power button on the remote controller forthe CS tuner (not shown). When the user wants to change a channel, theuser pushes at least one button for channel change operation. Aninfrared signal from the remote controller is converted into a wirelesssignal by the video receiver (communication station A 1100), and thewireless signal is transmitted to the video transmitter (communicationstation B 2100) to control the CS tuner (device b 2400).

Note that, if changing channels of the CS tuner (device b 2400) can berealized by a single button operation on the remote controller for theCS tuner (not shown) (for example, if each push of a certain buttonchanges one channel to another in descending order), it is possible toarrange such that switching between the devices and change of channelsis performed with the remote controller for the video receiver(controller A 1200) only.

Specifically, upon user's switching operation with the remote controllerfor the video receiver (controller A 1200), if there is any channelwhich has not been selected yet in the CS tuner (device b 2400),switching to a device to be selected next, i.e. hard disk recorder(device c 2500) is not carried out. Instead, changing only to thechannel not having been selected yet in the CS tuner is carried out.After completion of selection of all channels in the CS tuner (device b2400), only when the user performs switching operation with the remotecontroller for the video receiver (controller A 1200), switching to thehard disk recorder (device c 2500) is carried out. The same arrangementmay be realized by another device to which a concept of receptionchannels is applicable, such as BS tuner and terrestrial tuner.

Still further, the hard disk recorder (device c 2500) is also operatedin the same manner as the above case. After the user switches to thehard disk recorder (device c 2500) with the remote controller for thevideo receiver (controller A 1200), the user picks up the remotecontroller for the hard disk recorder (not shown) to operate the harddisk recorder with it. Here, when the user wants to turn on the harddisk recorder, the user pushes a power button on the remote controllerfor the hard disk recorder (not shown). When the user wants to change afile to view, the user pushes at least one button for channel changeoperation. An infrared signal from the remote controller is convertedinto a wireless signal by the video receiver (communication station A1100), and the wireless signal is transmitted to the video transmitter(communication station B 2100) to control the hard disk recorder (devicec 2500).

Note that, if changing files in the hard disk recorder (device c 2500)can be realized by a single button operation on the remote controllerfor hard disk recorder (not shown) (for example, if each push of acertain button changes one file to another in descending order of filenames), the following operation is carried out. Upon user's switchingoperation with the remote controller for the video receiver (controllerA 1200), if there is any file that has not been selected yet in the harddisk recorder (device c 2500), switching to the VCR (device a 2300) isnot carried out. Instead, changing only to the file not having beenselected yet in the hard disk recorder (device c 2500) is carried out.After completion of selection of all files in the hard disk recorder(device c 2500), only when the user performs switching operation withthe remote controller for the video receiver (controller A 1200),switching to the VCR (device a 2300) is carried out. The samearrangement may be realized by another device to which a concept thatone file is selected and viewed from among a plurality of files, such asa slave station in a system of downloading and viewing a file stored inthe server on the Internet.

Note that, the present invention is a content selection method whichselects a content from among transmission contents that a plurality ofcommunication stations have and may be arranged such that thetransmission contents are selected without consideration given todifferences between the communication stations that have thetransmission contents.

Further, in the above arrangement, the present invention may be arrangedsuch that selection of contents starts from a content in onecommunication station, and if all the contents to be selected in thecommunication station are selected, contents in a next station are thenselected sequentially.

Still further, in the above arrangement, the present invention may bearranged such that selection of a communication station is performed ina predetermined order (ascending order).

Yet further, in the above arrangement, the present invention may bearranged such that selection of a communication station is performed ina reversed order of the predetermined order (descending order).

Further, in the above arrangement, the present invention may be arrangedsuch that if a normal communication with a selected communicationstation is impossible for the reason of a poor communication, failure tomake a response caused by power-off of the selected communicationstation, or other reason, a content of the selected communicationconcerned is not selected, but a station to be selected next isselected.

Still further, in the above arrangement, the present invention may bearranged such that selection of contents is performed in a predeterminedorder (ascending order).

Yet further, the present invention may be arranged such that selectionof contents is performed in a reversed order of the predetermined order(descending order).

Further, in the above arrangement, the present invention may be arrangedsuch that if a normal reception of a selected content is impossible forthe reason of a poor communication, failure to make a response caused bypower-off of the selected device, or other reason, the content concernedis not selected, but a content to be selected next is selected.

Still further, the present invention is a control device and may bearranged so as to carry out a content selection using the foregoingcontent selection method with one action given to the control device.

Yet further, in the above arrangement, the present invention may bearranged such that as to an order in which contents are selected,control buttons are made corresponded to ascending order and descendingorder, respectively, so that contents are selected in ascending order ordescending order.

Further, the present invention is a communication system and may bearranged such that selection of contents according to the foregoingcontent selection method is carried out by transmission of a “switching”command to the transmission station concerned.

Still further, the present invention is a communication station and maybe arranged such that selection of contents according to the foregoingcontent selection method is carried out at the time of reception of theabove-arranged “switching” command.

Yet further, the present invention is a communication station and may bearranged such that selection of contents according to the foregoingcontent selection method is carried out at the time of reception of theabove-arranged “switching” command.

Note that, between the plug section 204 and one device in FIG. 13,necessary are a communication pathway for video transmission and acommunication pathway for control signal transmission. For thesecommunication pathways, one communication pathway may be shared, or aplurality of communication pathways may be used independently. Further,one communication pathway may allow information transmission/receptionin two directions, or may allow information transmission/reception ineither one of the two directions. Still further, connection of thesecommunication pathways may be wireless connection or wired-connection,and any protocol scheme can be used.

Descriptions of the present embodiment assume that transmission of avideo is carried out through wired connection such as RCA cable, Scable, or D-terminal cable, and transmission of a control signal iscarried out through an infrared remote control signal. However, anotherconnection pattern may be adopted.

If the plug section and the device are connected through the IEEE1394,video transmission and control signal transmission can be performedthrough one communication pathway, and it is conceivable that a video istransmitted as IEEE1394's Isochronous packet, and a control signal istransmitted using an AV/C protocol.

Other conceivable connection patterns to be used between communicationstations and between a communication station and a device are, forexample, radio waves in 2.4 GHz, 5 GHz band, or UWB (Ultra Wide Band),and light such as infrared light in a physical layer through wirelesscommunications. A conceivable MAC-layer protocol to be used is wirelessLAN (IEEE 802.11) or the like.

Further, a plurality of the plug section 204 may be provided in onecommunication station. Still further, the plug sections may adoptmutually different connection patterns.

Further, in the above arrangement, the present invention may be arrangedsuch that if a normal communication with a selected content isimpossible for the reason of a poor communication, failure to make aresponse caused by power-off of a selected providing device, or otherreason, the content concerned is not selected, but a content to beselected next is selected.

Still further, the local communication station, the device, and thedisplay device may be arranged to be integrated into one unit, and theremote communication station, the device, and the display device may bearranged so as to be integrated into one unit. Yet further, the localcommunication station and the remote communication station may beintegrated into one unit. In any arrangements, selection of devices canbe performed in the same manner.

The case where communication is poor means a case where strength ofelectric wave from a transmission station is lower than a predeterminedvalue, a case where an error ratio regarding a packet received by areception station excesses a given value, and/or a case where thereoccurs interference from other device.

Note that, unlike the foregoing descriptions, instead of preparation ofdevices dedicated for communication station, for each communicationstation, a personal computer and a piece of software (computerapplication) which operates therein may be substituted. In such a case,the software should be stored appropriately in an external storagedevice, and is read into a storage device such as RAM (Random AccessMemory) by a CPU (Central Processing Unit) of the personal computer.

Further, the present invention is applicable to a network structured byusing a plurality of content providing stations and a plurality ofcontent requesting stations.

It should be noted that a content selection method, according thepresent invention, in which a content selection requesting stationselects from among a plurality of content providing stations, mayinclude the steps of: the content selection requesting station storing aselection rule regarding the content providing stations; the contentselection requesting station receiving a content selection requestentered by an operator; the content selection requesting stationselecting one of the content providing stations in accordance with theselection rule; and the content selection requesting stationtransmitting the content selection request to thus selected one of thecontent providing stations.

With this arrangement, when the operator enters the content selectionrequest into the content selection requesting station, the contentselection requesting station selects a content in one of the contentproviding stations in accordance with the selection rule. Thus, theoperator is only required to know which content he wants to select, andis not required to know which station has the content he wants toselect. Thus, it is possible to select the desired content easily evenif the contents are located at a plurality of the stations in thedistributed manner.

Furthermore, the content selection method according to the presentinvention may include the step of sending back a content held by thecontent providing station, from the content providing station that hasreceived the content selection request, to the content selectionrequesting station.

With this arrangement, the content providing station selected inaccordance with the selection rule sends back the content that it has,to the content selection requesting station. Therefore, the operator canobtain the contents of the content providing stations simply by enteringthe content selection request into the content selection requestingstation. Thus, it is possible to select the desired content more easily.

Further, the content selection method according to the present inventionmay be arranged such that the selection rule regarding the contentproviding stations, which is stored in the content selection requestingstation, is to reselect a content providing station that has beenselected first, after selecting all the content providing stationstargeted for selection.

With this arrangement, after all the content providing stations targetedfor selection have been selected, the content providing station that wasselected first is reselected. Therefore, it is always possible to selectall the content providing stations regardless of which one of thecontent providing stations is selected first. Therefore, it is possibleto select the desired content more easily.

Furthermore, the content selection method according to the presentinvention may include the steps of if there still remains a content toselect, the thus selected one of the content providing stationsselecting, in accordance with a predetermined content selection ruleregarding, a content to select next, and the thus selected one of thecontent providing stations transmitting what is contained in the contentto select next, to the content selection requesting station; and ifthere remains no content that is to select, the thus selected one of thecontent providing stations transmitting information that there remainsno content to select.

In this arrangement, according to the selection rule, if there remainsany content in a given content providing station, the content isselected, and if there remains no content, the content selectionrequesting station is notified that there remains no content. Thisensures checking of all the contents in the content providing stations.Thus, it is possible to select the desired content more easily.

Moreover, the content selection method according to the presentinvention may include the steps of the content selection requestingstation confirming (i) a communication state regarding communicationbetween the content selection requesting station and the thus selectedone of the content providing stations, and (ii) a response stateregarding responding from the thus selected one of the content providingstations; and if the communication state is less than a desired level,the content selecting requesting station selecting a content providingstation to select next in accordance with the selection rule regardingthe content providing stations.

In the arrangement, the content selection requesting station skips thecontent providing station with which the content selection requestingstation cannot communicate in a good communication state, and transmitsthe content selection request to the content providing station to beselected next. Therefore, it is possible to arrange such that only thecontents of the content providing stations with which the contentselection requesting station can communicate in a good communicationstate can be the candidates of the contents to be selected. Therefore,the content selection can be performed more quickly.

Further, the content selection method according to the present inventionmay be arranged such that the content providing station confirming (i) acommunication state regarding communication between the contentproviding station and the selected content and (ii) a response stateregarding responding with respect to the selected content; and if thecommunication state is less than a desired level, the content providingstation sending back a content that is to be selected next in accordancewith the content selection rule.

In this arrangement, the content providing station skips the contentwith which the content providing station cannot communicate in a goodcommunication state, and selects the content that is to be selectednext. Therefore, it is possible to arrange such that only the contentswith which the content providing station can communicate in a goodcommunication state can be the candidates of the contents to beselected. Therefore, the content selection can be performed morequickly.

Furthermore, the content selection method according to the presentinvention may include the steps of: the content selection requestingstation confirming (i) a communication state regarding communicationbetween the content selection requesting station and the thus selectedone of the content providing stations, and (ii) a response stateregarding responding from the thus selected one of the content providingstations; and if the communication state is less than a desired level,the content selecting requesting station providing, to the operator,information that the communication state is less than the desired level.

In this arrangement, as to the content providing station with which thecontent selection requesting station cannot communicate in a goodcommunication state, the content selection requesting station providesto the operator information that the communication state is not goodbetween the content selection requesting station and that contentproviding station. This allows the operator to recognize that there isthe content providing station with which the content selectionrequesting station cannot communicate in a good communication state.With this, the operator can quickly take necessary actions such asimproving the communication state.

Moreover, the content selection method according to the presentinvention may includes the steps of the content providing stationconfirming (i) a communication state regarding communication between thecontent providing station and the content thus selected, and (ii) aresponse state regarding responding with respect to the content thusselected; if the communication state is less than a desired level, thecontent providing station transmitting, to the content selectionrequesting station, information that the communication state is lessthan a desired level; the content selection requesting station receivingthe information; and the content selection requesting station providing,to the operator, information that the communication state between thecontent providing station and the content thus selected is less than adesired level.

In this arrangement, as to the content with which the content providingstation cannot communicate in a good communication state, the contentproviding station transmits, to the content selection requestingstation, information that the communication state with the content isnot good. Then, the content selection requesting station provides theinformation to the operator. This allows the operator to recognize thatthere is the content with which the content providing station cannotcommunicate in a good communication state. With this, the operator canquickly take necessary actions such as improving the communicationstate.

Further, the content selection method according to the present inventionmay be arranged such that the state where the communication state isless than a desired level is a state where communication is possible butone of electric wave strength, the response state, and a communicationerror ratio is less than the desired level.

In the arrangement, the communication state that is less than a desiredlevel is a state where communication is possible but one of electricwave strength, the response state, and a communication error ratio isless than the desired level. Therefore, the selection from among thecontent providing stations may be carried out considering not onlywhether or not the communication is possible, but also whether or notthe communication state is good. Thus, it is possible to select thedesired content more easily.

Further, the content selection method according to the present inventionmay be arranged such that the state where the communication state isless than a desired level is (i) a state where a station at the otherend is not turned on, or (ii) a state where no response is receivedbecause the station at the other end becomes too distant.

In the arrangement, the communication state that is less than a desiredlevel is (i) a state where a station at the other end is not turned on,or (ii) a state where no response is received because the station at theother end becomes too distant. Therefore, it is possible to arrange suchthat the selection can be carried out only among the content providingstations that are turned on. Thus, it is possible to select the desiredcontent more easily.

Moreover, the content selection method according to the presentinvention may be arranged such that in providing, to the operator,information that the communication state between the content selectionrequesting station and the selected one of the content providingstations is less than the desired level, when the communication level isas such, the content selection requesting station distinctly informingthe operator whether the communication state is (A) a communicationstate where communication is possible but one of electric wave strength,the response state, and a communication error ratio is less than thedesired level, or (B) a communication state where (i) a station at theother end is not turned on, or (ii) no response is received because thestation at the other end becomes too distant.

Furthermore, the content selection method according to the presentinvention may be arranged such that in providing, to the operator,information that the communication state between the content selectionrequesting station and the content thus selected is less than thedesired level, when the communication level is as such, the contentselection requesting station distinctly informing the operator whetherthe communication state is (A) a communication state where communicationis possible but one of electric wave strength, the response state, and acommunication error ratio is less than the desired level, or (B) acommunication state where (i) a station at the other end is not turnedon, or (ii) no response is received because the station at the other endbecomes too distant.

Further, the content selection method according to the present inventionmay include the steps of transmitting a content switching instruction tothe content selection requesting station in accordance with an entry ofthe operator; and transmitting the content switching instruction fromthe content selection requesting station, which has received the contentswitching instruction, to a content providing station.

With this arrangement, the operator is only required to always performthe same operation and send the same instruction to the contentselection requesting station. Each station judges whether or not thecontent providing station still has the content to select and whether ornot there still remains an unselected content providing station. If thecontent providing station has no more content providing station orcontent to select, the station or content is switched to the contentproviding station to be selected next or the content to be selectednext. Thus, the operator is only required to do the same operation suchas pushing the same button, turning the same dial in the same direction,or the like operation, and it is unnecessary to perform again thestation selection operation and go back to the content selectionoperation, every time the content providing stations are switched over.Therefore, it is possible to select the desired content more easily.

Moreover, a content selection requesting station which selects a desiredcontent from among contents that a plurality of content providingstations have, may be arranged. such that the content selectionrequesting station transmits a content selection request to the contentproviding stations according to the foregoing methods.

With this arrangement, the content selection requesting stationtransmits the content selection request to the content providingstation, and receives, one by one, what are contained in the contentsthat the content providing station has. Thus, the operator is onlyrequired to know which content he wants to select, and is not requiredto know which station has the content he wants to select. Thus, it ispossible to select the desired content easily even if the contents arelocated at a plurality of the stations in the distributed manner.

Moreover, a content providing station according to the present inventionwhich, when selected by a content selection requesting station,transmits, to the content selection requesting station, what iscontained in a content that the content providing station has, may bearranged such that the content providing station receives a contentselection request from the content selection requesting stationaccording to the foregoing methods.

With this arrangement, if the content providing station is selected bythe content selection requesting station, the content providing stationselects, one by one, the contents that it has, and then the contentproviding station transmits, to the content selection requestingstation, what are contained in the contents. Thus, the operator is onlyrequired to know which content he wants to select, and is not requiredto know which station has the content he wants to select. Thus, it ispossible to select the desired content easily even if the contents arelocated at a plurality of the stations in the distributed manner.

Furthermore, a content switching instruction device according to thepresent invention may be for use in the foregoing methods and transmit,to the content selection requesting station, a content switchinginstruction given by the operator.

With this arrangement, the operator is only required to always performthe same operation and send the same instruction to the contentselection requesting station. Each station judges whether or not thecontent providing station still has the content to select and whether ornot there still remains an unselected content providing station. If thecontent providing station has no more content providing station orcontent to select, the station or content is switched to the contentproviding station to be selected next or the content to be selectednext. Thus, the operator is only required to do the same operation suchas pushing the same button, turning the same dial in the same direction,or the like operation, and it is unnecessary to perform again thestation selection operation and go back to the content selectionoperation, every time the content providing stations are switched over.Therefore, it is possible to select the desired content more easily.

Note that a content selection method according to the present inventionfor selecting, via a content selection requesting station, a desiredcontent from among contents that a plurality of content providingstations have may include the steps of: the content selection requestingstation storing an order of selecting the content providing stations;the content providing station storing an order of selecting contentsthat it has, the content selection requesting station receiving acontent selection request entered by an operator; the content selectionrequesting station transmitting the content selection request to one ofthe content providing stations in accordance with the order of selectingthe content providing stations; if the content providing station thathas received the content selection request still has a content to beselected next in accordance with the order of selecting the contents,the content providing station selecting the content to be selected nextand transmitting, to the content selection requesting station, what iscontained in the content; if the content providing station that hasreceived the content selection request has no more content to beselected, the content providing station transmitting, to the contentselection requesting station, information that the content providingstations has no more content to be selected; if received the informationthat the content providing stations has no more content to be selected,and if there remains a content providing station to be selected next inaccordance with the order of selecting the content providing stations,the content selection requesting station transmitting the contentselection request to the content providing station to be selected next;if received the information that the content providing stations has nomore content to be selected, and if there remains no content providingstation to be selected next in accordance with the order of selectingthe content providing stations, the content selection requesting stationtransmitting the content selection request to a content providingstation that has selected first.

With this arrangement, every time the operator performs, via the contentselection requesting station, the operation of switching among thecontents, the contents in one of the content providing station areselected one by one. If there are no more contents to select, thecontent providing station to be selected next is selected. In this way,the contents and the content providing stations are switched over. Thus,the operator is only required to know which content he wants to select,and is not required to know which station has the content he wants toselect. Thus, it is possible to select the desired content easily evenif the contents are located at a plurality of the stations in adispersed manner.

Moreover, in addition to the above arrangement, the content selectionmethod according to the present invention may be so arranged as toinclude the steps of the content selection requesting station judgingwhether the communication state between the content selection requestingstation and the selected one of the content providing station is good orpoor; and if poor, the content selection requesting station avoiding theselection of that content providing station and transmitting the contentselection request to the content providing station to be selected next.

In this arrangement, the content selection requesting station skips thecontent providing station with which the content selection requestingstation cannot communicate in a good communication state, and transmitsthe content selection request to the content providing station that isto be selected next. Therefore, it is possible to arrange such that onlythe contents of the content providing station with which the contentselection requesting station can communicate in a good communicationstate can be the candidates of the contents to be selected. Therefore,the content selection can be performed more quickly, in addition to theeffect of the above arrangement.

Moreover, in addition to the above arrangement, the content selectionmethod according to the present invention may be so arranged as toinclude the steps of: the content selection requesting station judgingwhether the communication state between the content selection requestingstation and the selected one of the content providing station is good orpoor; and if poor, the content selection requesting station providing,to the operator, information that the communication state is poor.

In this arrangement, as to the content providing station with which thecontent selection requesting station cannot communication in a goodcommunication state, the content selection requesting station provides,to the operator, information that the communication state is not goodbetween the content selection requesting station and that contentproviding station. This allows the operator to recognize that there isthe content providing station with which the content selectionrequesting station cannot communicate in a good communication state.With this, the operator can quickly take necessary actions such asimproving the communication state, in addition to the effect of theabove arrangement.

Moreover, in addition to the above arrangement, the content selectionmethod of the present invention may be so arranged as to include thesteps of: the content providing station judging whether thecommunication between the content providing station and the selected oneof the contents is good or poor; if poor, the content providing stationavoiding the selection of that content and selecting a content to beselected next.

With this arrangement, the content providing station skips the contentwith which it cannot communicate in a good communication state, andselects the content to select next. Therefore, it is possible to arrangesuch that only the contents with which the content providing station cancommunicate in a good communication state can be the candidates of thecontents to be selected. Therefore, the content selection can beperformed more quickly, in addition to the effect of the abovearrangement.

Moreover, in addition to the foregoing arrangement, the contentselection method of the present invention can be so arranged as toinclude the steps of the content providing station judging whether thecommunication between the content providing station and the selected oneof the contents is good or poor; if poor, the content providing stationtransmitting, to the content selection requesting station, informationthat the communication is poor; and if the content selection requestingstation receives the information, the content selection requestingstation provides, to the operator, the information that thecommunication is poor.

With the above arrangement, as to the content with which the contentproviding station cannot communicate in a good communication state, thecontent providing station provides, to the content selection requestingstation, information that the communication between the contentproviding station and the content is poor. Then, the content selectionrequesting station provides, to the operator, the information that thecommunication between the content providing station and the content ispoor. This allows the operator to recognize that there is the contentwith which the content providing station cannot communicate in a goodcommunication state. With this, the operator can quickly take necessaryactions such as improving the communication state, in addition to theeffect of the above arrangement.

Furthermore, in addition to the above arrangement, the content selectionmethod according to the present invention may be so arranged as toinclude transmitting a content switching instruction to the contentselection requesting station in accordance with an entry of theoperator; and transmitting the content switching instruction from thecontent selection requesting station, which has received the contentswitching instruction, to a content providing station.

With this arrangement, the operator is only required to always performthe same operation and send the same instruction to the contentselection requesting station. Each station judges whether or not thecontent providing station still has the content to select and whether ornot there still remains an unselected content providing station. If thecontent providing station has no more content providing station orcontent to select, the station or content is switched to the contentproviding station to be selected next or the content to be selectednext. Thus, the operator is only required to do the same operation suchas pushing the same button, turning the same dial in the same direction,or the like operation, and it is unnecessary to perform again thestation selection operation and go back to the content selectionoperation, every time the content providing stations are switched over.Therefore, it is possible to select the desired content more easily, inaddition to the effect of the above arrangement.

A content switching instruction device according to the presentinvention may be for use in the foregoing methods, and transmit, to thecontent selection requesting station, a content switching instructiongiven by the operator.

With this arrangement, the operator is only required to always performthe same operation and send the same instruction to the contentselection requesting station. Each station judges whether or not thecontent providing station still has the content to select and whether ornot there still remains an unselected content providing station. If thecontent providing station has no more content providing station orcontent to select, the station or content is switched to the contentproviding station to be selected next or the content to be selectednext. Thus, the operator is only required to do the same operation suchas pushing the same button, turning the same dial in the same direction,or the like operation, and it is unnecessary to perform again thestation selection operation and go back to the content selectionoperation, every time the content providing stations are switched over.Therefore, it is possible to select the desired content more easily, inaddition to the effect of the above arrangement.

Moreover, a content selection system according to the present invention,which selects, via a content selection requesting station, a desiredcontent from among contents that a plurality of content providingstations have, can be arranged such that the contents of the contentproviding stations are selected via the content selection requestingstation according to the foregoing content selection method.

In this arrangement, the content selection requesting station transmitsthe content selection request to the content providing station. When thecontent providing station receives the content selection request fromthe content selection requesting station, the content providing stationselects, one by one, the contents that it has, and transmits, one byone, what are contained in the contents, to the content selectionrequesting station. From the content providing station, the contentselection requesting station receives, one by one, what are contained inthe contents that the content providing station has. Thus, the operatoris only required to know which content he wants to select, and is notrequired to know which station has the content he wants to select. Thus,it is possible to select the desired content easily even if the contentsare located at a plurality of the stations in the distributed manner.

A content selection requesting station, according to the presentinvention, which selects a desired content from among contents that aplurality of content providing stations have, can be arranged such thatthe content selection requesting station transmits a content selectionrequest to the content providing station according to the foregoingmethods.

According to this arrangement, the content selection requesting stationtransmits the content selection request to the content providingstation, and receives, one by one, what are contained in the contentsthat the content providing station has. Thus, the operator is onlyrequired to know which content he wants to select, and is not requiredto know which station has the content he wants to select. Thus, it ispossible to select the desired content easily even if the contents arelocated at a plurality of the stations in the dispersed manner.

A content providing station, according to the present invention, which,when selected by a content selection requesting station, transmits, tothe content selection requesting station, what is contained in a contentthat the content providing station has, may be arranged such that thecontent providing station receives a content selection request from thecontent selection requesting station according to the foregoing methods.

According to this arrangement, if the content providing station isselected by the content selection requesting station, the contentproviding station selects, one by one, the contents that it has, andthen the content providing station sends, to the content selectionrequesting station, what are contained in the contents. Thus, theoperator is only required to know which content he wants to select, andis not required to know which station has the content he wants toselect. Thus, it is possible to select the desired content easily evenif the contents are located at a plurality of the stations in thedispersed manner.

Moreover, a program according to the present invention causes a computerto implement any one of the foregoing arrangements.

Furthermore, a computer-readable recording medium storing a programaccording to the present invention causes a computer to implement anyone of the foregoing arrangements.

Furthermore, a network system according to the present invention may bestructured by including a plurality of the content selection requestingstations of any one of these arrangements, and a plurality of thecontent providing stations of any one of these arrangements, and byusing any one of these content selection methods.

Moreover, a network system according to the present invention can bestructured by including a plurality of the content selection requestingstation and a plurality of the content providing stations, and by usingany one of these content selection methods.

With this arrangement, the operator is only required to know whichcontent he wants to select, and is not required to know which stationhas the content he wants to select. Thus, it is possible to select thedesired content easily even if the contents are located at a pluralityof the stations in the dispersed manner.

The invention being thus described, it will be obvious that the same waymay be varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

INDUSTRIAL APPLICABILITY

According to a content selection method of the present invention, in anarrangement where communication devices are located respectively in aroom where a video recording/reproducing device (such as a video tapedeck, a DVD player, or the like), for example, is placed and in a roomwhere an operator is, even if video recording/reproducing devicestargeted for remote control are located at a plurality of stations in adispersed manner, a desired video recording/reproducing device can beeasily selected. Thus, for example, in a situation where an operator isin a room where there is a television receiver, but not a DVD player,the operator operates a DVD player placed in another room throughcommunications, thereby viewing images of the DVD player on thetelevision receiver placed in the room where the operator is. Asdescribed above, the present invention is suitably applicable to an AVsystem provided with a plurality of video recording/reproducing devices,especially to a network system in which a video is transmittedwirelessly.

1. A content selection method in which a content selection requestingstation selects from among a plurality of content providing stations,comprising the steps of: the content selection requesting stationstoring a selection rule for selecting from among the content providingstations; the content selection requesting station receiving a contentselection request entered by an operator; the content selectionrequesting station selecting one of the content providing stations inaccordance with the selection rule; and the content selection requestingstation transmitting the content selection request to the thus selectedone of the content providing stations.
 2. The method as set forth inclaim 1, comprising the step of: sending back a content held by thecontent providing station, from the content providing station that hasreceived the content selection request, to the content selectionrequesting station.
 3. The method as set forth in claim 1, comprisingthe steps of: the content selection requesting station storinginformation for specifying a content providing station and an associatedcontent that have been most recently selected by the content selectionrequesting station; and the content selection requesting stationresuming, in accordance with the information, connection with thecontent providing station and the associated content that have been mostrecently selected by the content selection requesting station.
 4. Themethod as set forth in claim 1, comprising the step of: the contentselection requesting station storing information for specifying acontent providing station that has been most recently selected by thecontent selection requesting station; the content providing stationstoring information for specifying an associated content that has beenmost recently selected by the content selection requesting station; andresuming, in accordance with these sets of information, connectionbetween the content selection requesting station and the contentproviding station that has been most recently selected by the contentselection requesting station.
 5. The method as set forth in claim 4,wherein: if explicitly disconnected by the content selection requestingstation, or if having performed no video transmission to the contentselection requesting station for a certain period from a last time thecontent providing station has performed video transmission to thecontent selection requesting station, the content providing stationerases the information, which is stored by the content providingstation, for specifying the content that has been most recently selectedby the content selection requesting station.
 6. The method as set forthin claim 5, wherein: if having performed no video transmission to thecontent selection requesting station for a certain period from a lasttime it has performed video transmission to the content selectionrequesting station, the content providing station erases theinformation, which it stores, for specifying the content that has beenmost recently selected by the content selection requesting station. 7.The method as set forth in claim 2, wherein: the content providingstation transmits, to the content selection requesting station,information regarding a content that is to send back to the contentselection requesting station.
 8. The method as set forth in claim 2,wherein: the content providing station transmits, to the contentselection requesting station, information regarding a content that isavailable to be selected next by the content selection requestingstation.
 9. The method as set forth in claim 2, wherein: the contentproviding station transmits, to the content selection requestingstation, information regarding a content that is available to beselected by the content selection requesting station.
 10. The method asset forth in claim 1, wherein: the selection rule regarding the contentproviding stations, which is stored in the content selection requestingstation, is to reselect a content providing station that has beenselected first, after all the content providing stations targeted forselection are selected.
 11. The method as set forth in claim 1,comprising the steps of: if there still remains a content to select, thethus selected one of the content providing stations selecting, inaccordance with a predetermined content selection rule, a content toselect next, and the thus selected one of the content providing stationstransmitting what is contained in the content to select next, to thecontent selection requesting station; and if there remains no contentthat is to select, the thus selected one of the content providingstations transmitting information that there remains no content toselect.
 12. The method as set forth in claim 1, wherein: when receivingthe information that there remains no content to select, the contentselection requesting station changes a content providing stationconnected to the content selection requesting station, in accordancewith the selection rule for selecting from among the content providingstations.
 13. The method as set forth in claim 1, comprising the stepsof: the content selection requesting station confirming (i) acommunication state regarding communication between the contentselection requesting station and the thus selected one of the contentproviding stations, and (ii) a response state regarding responding fromthe thus selected one of the content providing stations; and if thecommunication state is less than a desired level, the content selectingrequesting station selecting a content providing station to select nextin accordance with the selection rule for selecting from among thecontent providing stations.
 14. The method as set forth in claim 2,wherein: the content providing station confirming (i) a communicationstate regarding communication between the content providing station anda content that is to send back and (ii) a response state regardingresponding with respect to the content that is to send back; and if thecommunication state is less than a desired level, the content providingstation sending back a content that is to be selected next in accordancewith a predetermined content selection rule.
 15. The method as set forthin claim 2, comprising the step of: in the case where bandwidthavailable for communication between the content selection requestingstation and the content providing station is narrower than bandwidthnecessary for transmitting a content that the content providing stationis about to send back, the content providing station transmitting acontent that is to be selected next to the content that the contentproviding station is about to send back, in accordance with the apredetermined content selection rule.
 16. The method as set forth inclaim 2, comprising the step of: in a state where a content that thecontent providing station is about to send back is in use, the contentproviding station sending back a content that is to be selected next tothe content that the content providing station is about to send, inaccordance with a predetermined content selection rule.
 17. The methodas set forth in claim 16, wherein: the state where the content is in useis a state where the content is being used by another content selectionrequesting station, or a state where a user on the content providingstation side is using the content without using the content selectionrequesting station.
 18. The method as set forth in claim 1, comprisingthe step of: the content selection requesting station confirming (i) acommunication state regarding communication between the contentselection requesting station and the thus selected one of the contentproviding stations, and (ii) a response state regarding responding fromthe thus selected one of the content providing stations; and if thecommunication state is less than a desired level, the content selectionrequesting station providing, to the operator, information that thecommunication state is less than the desired level.
 19. The method asset forth in claim 1, comprising the steps of: the content providingstation confirming (i) a communication state regarding communicationbetween the content providing station and the content thus selected, and(ii) a response state regarding responding with respect to the contentthus selected; if the communication state is less than a desired level,the content providing station transmitting, to the content selectionrequesting station, information that the communication state is lessthan a desired level; the content selection requesting station receivingthe information; and the content selection requesting station providing,to the operator, information that the communication state between thecontent providing station and the content thus selected is less than adesired level.
 20. The method as set forth in claim 13, wherein: thestate where the communication state is less than a desired level is astate where communication is possible but one of electric wave strength,the response state, and a communication error ratio is less than thedesired level.
 21. The method as set forth in claim 13, wherein: thestate where the communication state is less than a desired level is (i)a state where a station at the other end is not turned on, (ii) a statewhere no response is received because the station at the other endbecomes too distant, or (iii) a state where the thus selected one of thecontent providing stations is physically disconnected from the content.22. The method as set forth in claim 18, wherein: in providing, to theoperator, information that the communication state between the contentselection requesting station and the selected one of the contentproviding stations is less than the desired level, when thecommunication level is as such, the content selection requesting stationdistinctly informing the operator whether the communication state is (A)a communication state where communication is possible but one ofelectric wave strength, the response state, and a communication errorratio is less than the desired level, or (B) a communication state where(i) a station at the other end is not turned on, (ii) no response isreceived because the station at the other end becomes too distant, or(iii) the content is physically disconnected.
 23. The method as setforth in claim 19, wherein: in providing, to the operator, informationthat the communication state between the content selection requestingstation and the content thus selected is less than the desired level,when the communication level is as such, the content selectionrequesting station distinctly informing the operator whether thecommunication state is (A) a communication state where communication ispossible but one of electric wave strength, the response state, and acommunication error ratio is less than the desired level, or (B) acommunication state where (i) a station at the other end is not turnedon, (ii) no response is received because the station at the other endbecomes too distant, or the content is physically disconnected.
 24. Themethod as set forth in claim 1, comprising the steps of: transmitting acontent switching instruction to the content selection requestingstation in accordance with an entry of the operator; and transmittingthe content switching instruction from the content selection requestingstation, which has received the content switching instruction, to acontent providing station.
 25. The method as set forth in claim 1,wherein: the content selection requesting station includes means whichcontrols switching of an external connection device for a display deviceon which the content received by the content selection requestingstation is to be displayed; if the content selection requesting stationis selected as the external connection device for the display devicewhen the content selection requesting station receives the contentselection request entered by the operator, the content selectionrequesting station performs content selection; and if all contents areselected once, or if a station other than the content selectionrequesting station is selected as the external connection device for thedisplay device, the switching of the external connection device iscarried out.
 26. The method as set forth in claim 1, wherein: theselection rule is stored only in the content selection requestingstation; and the content is held only by the content providing station.27. A content selection method in which in accordance with a requestfrom a content selection requesting station, a content providing stationsends back a content that the content providing station has, the methodcomprising the steps of: the content providing station storing a controlsignal for the content that the content providing station has; and if acontent to send back is not available for viewing, the content providingstation transmitting the control signal to the content so as to causethe content to be available for viewing.
 28. A content selection methodin which in accordance with a request from a content selectionrequesting station, a content providing station sends back a contentthat the content providing station has, the method comprising the stepsof: the content providing station storing a control signal for thecontent that the content providing station has; and when a content tosend back is changed from a first content to a second content, thecontent providing station transmitting a control signal to the firstcontent so as to cause the first content to be not in use.
 29. A contentselection requesting station which selects a desired content from amongcontents that a plurality of content providing stations have, wherein:the content selection requesting station transmits a content selectionrequest to the content providing station according to the method as setforth in claim
 1. 30. A content providing station which, when selectedby a content selection requesting station, transmits, to the contentselection requesting station, what is contained in a content that thecontent providing station has, wherein: the content providing stationreceives a content selection request from the content selectionrequesting station according to the method as set forth in claim
 1. 31.A content switching instruction device for use in the method as setforth in claim 1, which transmits, to a content selection requestingstation, a content switching instruction given by an operator.
 32. Thecontent switching instruction device as set forth in claim 31, thecontent switching instruction device transmitting the content switchinginstruction given by the operator, without using the content selectionrequesting station.
 33. A program for causing a computer to implementthe method as set forth in claim
 1. 34. A computer-readable recordingmedium storing a program for causing a computer to implement the methodas set forth in claim
 1. 35. A network system structured by having aplurality of the content selection requesting stations as set forth inclaim 29, and a plurality of the content providing stations as set forthin claim 30, and by using the method as set forth in claim 1.